Twitter's "Find Friends" section make it easier to find & follow people you already know -- your friends on Facebook and connections on LinkedIn -- who use Twitter.
"Our Facebook app, now shows which of your Facebook friends are on Twitter and lets you follow them instantly and save them to a list. The app also lets you post your Tweets to your Facebook profile and now, to one of your Facebook pages too. With Tweets application by LinkedIn, you can see which of your LinkedIn connections are on Twitter and follow the ones you choose right from the app. The app also lets you save your LinkedIn connections as a list, post your Tweets to LinkedIn, and add your Twitter account to your LinkedIn profile," explains Twitter.