Winner: Intersect by Abraham Williams
Williams came up with this cool extension for Chrome that shows additional information about a user’s followers on Twitter — in particular, it shows where you and another user’s social graphs overlap. Install the extension and visit somebody’s Twitter profile page. You’ll see additional grids loading below their stack of followers. You see which of your friends are also following that user, which friends you have in common and which followers you have in common. It’s an excellent social discovery tool for Twitter power users, and the best extension for Twitter’s stock web interface we’ve seen yet. Congrats, Abraham!