The Facebook Friend Wheel clusters your friends by their relations (made by thomas fletcher), this is mine (the lines in the circle are actually names but not visible in this detail level) but the app limits itself to 1000 friends.
I thought it was interesting enough to store on my blog to recreate some day. There should be lines visible showing the relations between me/your friends but these do not show in my diagram.
A while ago I wrote something like this for a community: I aggregated all user data in a database based on their Facebook information but never came to it, to do a visualization as above.
What I am thinking of is writing a piece of software that does that same as above but for A LOT of social networks and instead of around one person around multiple persons as center as to say in “inner circle” versus “outer circle” or even multiple circles around each other. These multiple layers of circles will then have their own “properties”.