Digg

From Digg:

Digg is a user driven social content Website. Everything on Digg is submitted by our community (that would be you). After you submit content, other people read your submission and Digg what they like best. If your story rocks and receives enough Diggs, it is promoted to the front page for the millions of visitors to see. Every person can digg (help promote), bury (help remove spam), and comment on stories.

You can even Digg and bury comments you like or dislike. Digg also allows you to track your friends' activity throughout the site, want to share a video or news story with a friend.

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