I love graph viewers and visualizers and being able to play with them on your own data is better than anything :-)
SpiderFriend is a visualizer for your facebook friends network, it graphs you and your immediate friends on the edge of a sphere with connections between y'all. Nice, but the visual treatment doesn't allow you to see clearly who knows who.
I'd also like to see a way to explore the network, clicking on a friend and seeing their friends and so on. I guess facebook apps can't wander around that easily :-(
Take a look at the short video below or download and play yourself from http://www.butant.com/spiderfriend/