I recently discovered http://www.urbanmobs.fr/ , which is a cool-looking visualization of mobile phone calls and sms.

I think Facebook's Palantir project also deserves an honorable mention here.

http://www.facebook.com/home.php#/video/video.php?v=37403547...

Real-time visualization of Facebook actions (pokes, friend request, etc).

While undoubtedly interesting, that's actually pretty average when it comes to the actual visualization.

If you've ever been to Google, you'll know that Palantir is a much smaller version of what they've had as a visualization for years. Props to them for putting it together so quickly, but it's certainly not a new visualization type. I'm also not 100% convinced it's real-time data.