Ebay Pop and BidThumbs show prices of items selling on Ebay as well as popular trends within a category.
Ebay Pop (via probargainhunter) lets you browse various categories to see the movers and shakers, including the most popular items in that category as well as items whose popularity has changed dramatically. The site explains it “is intended to capture some of the excitement of shopping on eBay in a fun, informative and creative way – with a twist of pop culture and current events.”
BidThumbs displays a page of thumbnails representing no reserve or reserve met items within a given category that will end in 24 hours. That way you can visit the site each day and see an entirely new set of items.
It’s fun to browse around both sites to see what items are selling and for how much.