So its a little dated (announced March 28th, 2006) but I recently came across a nice list of web 2.0 sites organized by category. Its actually a list of winners from the seomoz.org website and I could see myself killing a day or two playing with some of these links.
Some sites that I’ll be checking out :
wayfaring.com - Wayfaring allows you to create personal maps with and share them with your friends. Explore maps created by others and connect and collaborate over a vast social network. Mapmaking has never been so easy!
newsvine.com - Keep track of breaking news with Newsvine: read “The Wire” for a direct stream of articles from the AP and ESPN, and read “The Vine” for Newsvine user submitted content and columns. Interact with other Newsvine readers by voting for and commenting on news, and write/maintain your own Newsvine column.
cssbeauty.com - A project focused on providing its audience with a database of well designed CSS websites from around the world.