Just stumbled on 8Notes, a UK-based social network for musicians. You can upload your own music, share and download sheet music, and talk to other musicians via a lively forum.
They have a good-sized collection of not very printable musician jokes too. When I was learning classical violin many, many moons ago it was always viola jokes - from a quick glance round it looks like nothing much has changed...
http://www.8notes.com/
