There are lots of text fields out there that want you to enter a URL, but many of them think they’re doing you a favor by putting http:// in the field for you. I don’t find this helpful because I’m usually pasting the URL into the field, meaning I have to get rid of the http:// before I paste.
The site that set me off on this little rant is URL info.
An even better solution is to make the http:// optional, so if I am typing in a domain I can skip it and just enter the domain (e.g. google.com).
After writing that last part I checked the site and it automatically added the http:// to google.com. That makes it even more odd that they put it there in the first place, because it’s not necessary and gets in the way if you’re pasting.