Palantir, by Jack Lindamood, Kevin Der, and Dan Weatherford of Facebook, visualizes friend activity on Facebook. The three "hacked" together Palantir at Facebook's recent Hackathon, but I'd never guess that it was put together in just one night by looking at it. There are a few different views. One shows activity in the form of towers sprouting up from the ground and another visualizes interactions between Facebook friends with floating arcs and things that look like orbiting comets. The former reminds me of a visualization some Google folks did a while back but with search terms. I can't find a link to it now though (a little help, please?).
Anyways, the pictures aren't really enough to understand what I'm talking about. Watch the video for more.