Facebook Application Development
Facebook allows developers to create applications for the general use of Facebook users. For a proof-of-concept for a client I developed an easy Facebook-styled quiz in PHP and fed the results back to the Facebook server in their proprietary FBML language. One of the huge advantages of doing it this way is I can tap into the friends of the quiz-taker and display results that matched their friends. Facebook is all about social networking, and it was interesting to design a project that emphasized this aspect. It isn't live in Facebook yet, but it works.