Jam with others on the net in real-time

There's a tiny bit of latency when playing together but it's not noticable once you get into the groove. I played guitar with 3 or 4 other people - piano, bass, another guitar, and someone can turn on the drum machine. It was pretty fun. It works on the 3 major platforms - Mac, Windows and Linux, so maybe it could be used as a communications app also.

http://www.ninjam.com