Borrowing a page from Facebook, Andrew Odewahn put together a fun charting of the United State Senate's social graph going back to the 102nd Congress in 1991. "Friendship" here really means voting record affinity. Members are shown to share a connection if they voting together more than 65% percent of the time, and their proximity to one another is based on the level of agreement above and beyond that level. As Odewahn notes, one of the more interesting aspects is the clusters that develop within Republican and Democratic caucuses.

(A plug: Odewahn used GovTrack's scraped data to build his chart -- data that will be much easier to get now that the Senate has adopted XML for votes.)

Neat stuff. You know what I'd also love to see? Any actual social graph of the Senate showing who's attending whose weekend BBQ, playing squash together, and the like. As we've seen, who sits next to each other on Amtrak can be predictive of the very future of the Senate.