Facebook has a brimming library of applications (often referred to as "apps") for users to install to their profiles. The apps range from associating your Facebook account with your Twitter feed, to helping you organize your photos. Here are some favorites:
Recruit friends to raise money for your favorite charities with this application, which processes donations by credit card—and also posts the names of top fundraisers...like you!
You always thought you were a little bit Ringo, but your friends say you're a little bit George. Settle the question with this app, which determines your true inner Beatle.
Find family members who are Facebook users and build a virtual family tree. This application helps link distant relatives, making it easy to swap pictures and stay in touch.
See your friends' birthdays in calendar format, and send online cards from a selection of more than 1,700. You can receive e-mail and cell phone reminders, too.
Challenge your vocab-ulous friends to this online version of the beloved board game (and they won't see you checking the dictionary in between turns!).