Thomas Fletcher, a 19 year old student studying Computer Science & Maths at Bath University, has developed a series of Facebook applications. Among them is a colorful wheel that maps all the links between Facebook friends, in this case, between all of Thomas Fletcher's 100 friends.
Friend Wheel is free and anyone with a Facebook account can see their network of friends linked and represented in this fashion. The rationale is simple: On the outside are all of your friends and if two people are linked together, it means that they are friends with each other. There's also an interactive flash version which allows the nodes to be moved and highlighted, and makes it possible to zoom in and out.
At the time of writing, 31st August 2007, Friend Wheel had 365,000 users and is still growing significantly. Around 25,000 wheels are generated each day. The tool uses the Facebook Development Platform to retrieve your friends and all of the links between them. This information is then used to draw the wheel image. PHP and the GD extensions for drawing are used for Friend Wheel.