Snapzu - Snapzu is basically reddit alternative.
4chan - 4chan is a simple image-based bulletin board where anyone can post comments and share images.
Lainchan - Lainchan is a great imageboard package, actively building on it and adding a lot of features and...
Digg - Digg delivers the most interesting and talked-about stories on the Web right now.
Reddit - Reddit gives you the best of the internet in one place. Get a constantly updating feed of breaking news, fun stories, pics, memes, and videos just for you.
Linkibl - Linkibl is where you can discover and share the Internet's most interesting content every day.