So and So is now following you on Twitter. Who? How did they find me? Why might I want to follow back? That's been a common bit of internal dialogue for me lately. Often the answer lies in our mutual friends or followers. Social networks like LinkedIn and Facebook make this easy. Not so with Twitter, which is why I was excited to find Intersect.
From a user standpoint, it's a Google Chrome extension (Firefox apparently coming soon) that inserts a "mutual friends" and "mutual followers" section to profile pages on Twitter.com. You can see an example in the video embedded below.
More exciting than the Intersect browser extension is the underlying data--and the API that is behind it (our Intersect API profile). It's not as official as some APIs, but it's documented on the GitHub repository. It is also open source (MIT license), so you could run your own version of the service. .
The next step that would like to see is for Twitter app developers to incorporate it. Twimailer, the improved new follower email service, could let me know when we follow the same people. Twitter clients, such as my iPhone's Tweetie, could add it to the services menu.
There are already a few mashups that will give me mutual Twitter friends and followers. OMGFriends is one. MashedIn shows Twitter, as well as Facebook and LinkedIn. But now that there's an API, it would be great to see that functionality added to the places where I am more likely to act on the information.