Bram's most recent suggestion would be very easy indeed to implement, so I'd like to experiment with it, but I think results on random graphs wouldn't be very meaningful.
I'd most of all like to try the LJ friends graph, but I don't think they'd be up for making it downloadable...
(update: I tried to do a new diary entry, and it replaced this one! Bah! Fortunately I had edited this one and the old version was in my browser cache...)