Local storage is great. It’s fast, relatively inexpensive and under your control, but if a natural disaster strikes, on-site backups alone may not preserve your data. Having off-site backups has been expensive in the past, but dozens of free or inexpensive services have been created in the past few years. There are several flavors of services. Some are purely for backup (like Mozy), others are for backup and synchronization (like Dropbox) and others are for sending large files (like DropSend) as an alternative to email. I’ve compiled the following lists (separating out the image-only storage sites) which I’ll update periodically.

(Updated on 29 Feb 2012)

Synchronization

Dropbox – 2GB free, free option keeps old file revisions for 30 days, public folder for sharing, share any file, Windows, Linux, Mac support, 50GB for $9.99/month, 100GB for $19.99/month.
Memopal – 3GB free (plus an extra 500MB for both of us if you use this link), file revisions and deleted files never removed, 200GB for $49/year
Humyo – 10GB free (5GB for photos/videos/music, 5GB for everything else), $6.99/month or $69.99/year for 100GB, synchronization available with paid plan.
LiveKive (AVG) – 5GB free, Windows and Mac support
Live Mesh – 5GB free, remote desktop capability to hosts in the mesh.
Nomadesk – Backup and sync files with 5 PCs (Windows only), unlimited storage, bandwidth and file sizes. $50/year for personal storage, $15/month for group storage. Free trial available.
OpenDrive – 1GB free, syncing on other computers (syncs with Boxstr)
SugarSync – 5GB free on unlimited devices, 30GB for $4.99/month or $49.99/year, Windows and Mac support, free 30-day trial of full service
Syncplicity – 2GB free (limited to 2 computers) Windows and Mac support
Tilana – Free 2GB account for 12 months, $49.95/year per computer
Windows Live Sync P2P syncing up to 20,000 files per shared folder (No remote storage)

Online Storage

Adobe ConnectNow – 5GB free, multiple file upload, can link to files for sharing. Also has group collaboration features, like screen sharing, web cam, chat and word processor.
Adrive – Free, 50GB, windows backup client
AllMyData – $9.99/month or $99.99/year for unlimited bandwidth and storage, free 30-day trial
Amazon S3 – $0.15/GB storage, $0.20/GB transferred
Arkiva – 2GB free, lots of social networking features
BackBlaze – Unlimited, always on (meaning they’re not scheduled) full system backups for $5/month per computer (Windows only). Free trial available.
Backup Right – 50GB for $12.99/month (Windows or Mac)
Box.net – 1GB for free, 25MB file size and 10GB transfer a month. 5GB with 1GB file size and unlimited bandwidth for $7.95/mo, quasi-direct linking
Boxstr – 5GB free, direct linking
Carbonite – $49.95/year unlimited storage. Windows only, desktop client on one computer. Lost data of 7,500+ customers in 2009
Cucku – Find a backup buddy and mutually store backups (integrated with Skype)
Data bus – 10GB free, 1.5MB file limit, no transfer limit
Data deposit box – $2 per GB/month, unlimited computers and users. 14-day free trial
Data vault Corp – $9.95/month for 1GB of storage
Diino – 5GB free online storage, desktop client for Windows, Mac and Linux to mount shared drive
Diomede Storage – Online, nearly and offline storage (immediate access, < 5 minutes and < 4 hours respectively). Created by former MediaMax CEO Steve Iverson, invite code: tcrunch Divshare – 5GB free, 10GB transfer/month, no client, all web interface but has java applet with drag and drop facility.
Dreamhost – 50GB of storage space included in price of hosting (use promo code of AATW to get $50 off the first year of hosting)
DropBoks – 1GB free
Elephant Drive – 1GB free online storage, unlimited storage for $4.95/month.
Esnips – 5GB free (viewable on the web)
FileDen – Free 1GB, 50MB file-size limit, 5GB bandwidth limit
FileFreak – Free 1GB, 50MB file-size limit, 256MB daily bandwidth limit
FileQube – Store up to 2GB free (150MB file size limit)
FrostBytez – 50GB free (200MB file size limit)
Gmail Drive – Use your Gmail account for storage by mapping it to a drive (Windows only)
HP Upline – Unlimited storage for $59/year for one computer, Windows only.
iBackup – $9.95/month for 10GB, Windows and Mac
iDrive – 2GB free, windows/mac application, 150GB $4.95/month, $49.50/year, archives last 30 versions of a file (don’t count against quota), byte-level backup (only changed parts of file is uploaded).
Joggle – Can store photos, music, videos, and documents. Don’t know the details on storage space
JungleDisk – Software costs $20, free upgrades and unlimited computers. Works on Windows, Mac, Linux, powered by Amazon S3.
Kabooza – Swedish startup, Windows only, 25GB bandwidth/month, $49.95/year
Kadoo – 10GB free, free faxing, drag and drop multiple files for upload
KeepIt.com – $4.95/month for unlimited storage, 30 days of revisions saved
Lifestream – $4.95/month or $29.95/year for 20GB of storage. Used to back up social media sites (Twitter, Flickr, Google Docs, Photobucket etc), uses Amazon web services on the backend.
LiveDrive – 100GB storage for £39.95, unknown file size limits, but multiple GB files are allowed. Windows client lets mount the drive on your desktop.
MediaFire – Unlimited storage, 2GB file size, free, no registration required, available on the web
MegaUpload – Free, 50GB storage, 1GB file size
Mozy Remote Backup – 2GB free, unlimited storage for $4.95/month for one computer (Windows only), owned by EMC
Minus – 50MB per file limit, not sure on total limit, sharing, download all as zip, only supports certain file types
MyBloop – Unlimited storage, web upload
myDisk.se – 2GB free, Webdav support, Windows, Mac, Linux support, files may be removed on free accounts after a period of inactivity (not sure how long)
MyOtherDrive – 5GB free, 10GB transfers/month
Nakido – Unlimited storage and bandwidth, files remain forever, single file upload through web, multiple file upload with cross-platform (Windows, Mac, Linux) desktop client
NetMass $80/year for 10GB
Online Backup Vault – 3GB $6/month, $39 annual, other plans available
Oosah – 1TB free, only support certain media file types, integrates with Flickr, YouTube, Facebook and Picasa – uploading currently disabled (4 Feb 2009)
OrbitFiles – 6GB free, public or private, unlimited storage for $5/month
Putplace – 20GB €40/year, 30-day free trial
Rrsync.net – $1.20/GB month, unlimited transfers
SpiderOak – 2GB free, Windows, Mac, Linux
Steekr 1GB free, desktop clients for Windows and Mac
StrongSpace – 2GB free, 5GB for $15/month
SwapDrive – 10MB for $20/year, owned by Symantec
TunesBag – 5GB of music free, run by a PhD in law who says it’s okay to share with groups
Upit.To – No registration required but registration provides additional features. Unlimited files up to 5GB each, unused files removed after 30 days
Who.HasFiles – 100MB free network drive that can be mounted as a native drive from any computer without downloading any software.
Windows Live SkyDrive – 25GB free, 50MB per-file limit, can only upload individual files at a time unless you use Gladinet.
Wixi – Unlimited storage and streaming of media files from anywhere
Wonderfile – 1GB free, uses tags and categories instead of folders
Wuala – 1GB free drag and drop storage, get more by paying or trading your own disk space for online space. Windows, Mac and Linux
Yuntaa 1GB free, organizes your files by type, maintains revision history. Desktop client is Windows only.
Z Drive – 5GB free, virus scanning for uploads
ZumoDrive – 1GB free, mounts online storage as a local drive, but doesn’t require all the space at once. Good for devices (like laptops) that don’t have much storage that can act as a Window into the larger online space. Caches local versions as needed so they’re accessible if you’re offline. More space available for a fee.
4Shared – 5GB for free, deleted if you don’t login for 30 days, 2GB maximum file size

Image Storage

EchoPic – Store family friendly images, no restrictions, no registration required
Flickr – 100MB each month, up to 200 images visible at any given time for free. Premium account has unlimited photos (20MB per photo) for $25/year
Fotki – 50MB storage
Iimmgg – Direct linking, edit with Picnik, don’t know the limits on size and bandwidth
ImageBam – 3MB file size limit, unlimited number of images, no registration, direct linking
ImageShack – Store images up to 1.5MB, 300MB bandwidth/hour allowed, direct linking
Imgur – 2MB limit, direct linking, no registration, no ads, images kept forever (your IP address is stored)
Ipernity – 200MB of docs (images, documents, etc) per month
Picasa Web Album – 1GB free
Phanfare – 1GB of photos uploaded from web or iPhone
PiccDrop – 6MB file limit, no bandwidth limits, direct linking
Pict – No registration required, one-click upload, direct linking, JPG, GIF and PNG supported
Picupine – 5MB file limit, no registration required
Pikchur – Send photos from your mobile device
Photobucket – 25GB of bandwidth per month free, direct linking
Photomemo – Upload images by emailing post@photomemo.jp, with accompanying text in body of email.
TinyAlbum – 8MB (only JPG or PNG)
TinyPic – Up to 1600 pixels (height or width), 100MB for videos
Troovi – No registration required, 50 photos per collection, download all photos as a zip file, photos deleted if not used for 30 days, photos secured by the unique private URL (if the URL is know, photos can be seen)
Xs.To – Max file size 2MB

Sending files

2Large2Email – 200MB max file size, lasts 7 days, 100 downloads, 1GB bandwidth
AnyHub – 10GB max file size, no bandwidth limits
Crate – 200MB (with free registration) 50MB file limit.
Driveway – 500MB file limit (2GB total storage), no limit on downloads, files last for 90 days from last access
Drop.IO – Send up to 100MB, longest expiration is 1 year from last view – Bought by Facebook
DropSend – Free service allows 2GB files, 5 sends/month.
Dushare – Peer to peer, no registration required. Includes chat function with person you’re sharing a file with.
FileAI – Securely send files on peer to peer network connection that is never stored on the server. Both clients have to be online. No size limits
FileDropper – Free, files up to 5GB, no registration required
FileMail – Send files up to 2GB free
FilePhile – Unlimited P2P file transfers, but both users must have application (like Torrents)
FileSavr – Free file hosting, up to 10 GB
FileShaker – 10GB file size limit, files kept on server as long as they’re being downloaded.
Files Over Miles – Private URL for encrypted peer to peer file transfers in the browser. File size limited to amount of RAM on the machine.
FlyUpload – Free file sharing up to 2GB, no registration required
iFileIt – 250MB per file, easy for users to download, files remain as long as they’re downloaded
GigaSize – Free, unlimited files stored for 45 days, 600MB per file max
Hotfile – 400MB per file max, free
JetBytes – File is sent directly to another use without being stored on the server. Selecting a file generates a one time link. When the link is followed, the file is uploaded from your machine and downloaded to the recipient.
MailBigFile – 1 recipient, 200MB limit, 10 downloads, files last for 5 days
MyFreeFileHosting – Files up to 100MB, include recipient’s email address
Pando – P2P software allowing you to send files up to 1GB
Pipebytes – Send a file of any size to anyone, once they download it, it’s gone. Free version limited to 384 Kbit/sec transfer speed.
Planets DB – 50MB limit on file size
Podmailing – Unlimited P2P file transfers via http, bittorrent. Doesn’t require recipient to have application.
RapidShare – Annoying for free users, but said to be great for paid customers (I wouldn’t know)
Save As – Link good for 24 hours, no size restrictions
Send6 – 5 sends per month (not 6? :)), 100MB file limit, 250MB total limit, files expire after 7 days, 1GB bandwidth allowance
Sendeo – Send files up to 10MB, private and public links
Sendoid – P2P file sharing from your browser (using Adobe AIR app), limited by your hardware, but usually around 600MB to 1 GB according to their FAQ.
Sendspace – Send files up to 300MB, unlimited uploads and downloads
SendUIt – Free, no registration required, send files up to 100MB. Expiration from 30 minutes to 1 week.
Sharebee – 150MB limit, removed after 30 days of not being used
ShareSend – 100MB limit, no registration required, integrated with Twitter
SpreadIt – Send files up to 500MB, no registration required
StreamFile – Send files up to 150MB for free, using recipient’s email address
TransferBigFiles – Send files up to 1GB, file expires after 5-10 days, no registration required.
Uploading – 100MB file limit, no registration required
Usend.io – Uses drop.io as backend, so it has same limitations.
YouSendIt – Send files up to 100MB for free, limited to 100 downloads per file
WeTransfer – 2GB file size limit, no login required, sends you and recipient(s) an email, up to 20 recipients
Wikisend – 100MB limit, files last for 1-90 days, can password protect files
xFiles – P2P exchange of files directly (without uploading to an intermediate server)
Zapr – File sharing from your desktop. You create link to any file on your Windows computer and others can download it from the URL.
Ziddu – Send files up to 200GB for free, get paid $0.001 per download, payout by Paypal at $10. Files removed after 90 days if not downloaded.
zShare – Send files up to 100MB for free, unlimited downloads

Other Links

Detailed comparisons of storage services
New York Times: Don’t Keep All Your Data in One Stash
Byte and Switch: Sifting Through Online Backup Service Options
Lifehacker storage comparison chart