One of last year’s TechCrunch50 startups, Bojam, is launching in public beta today and we have 500 invites. Bojam is a Web-based sound studio that lets musicians practice playing music, find other musicians around the world to jam with, and lay down tracks together on the same song. Click here to try out the service.

Bojam is a fully functional music mixer. You can adjust the volume on each track or add effects like distortion and reverb. Similarly, you can solo or mute instruments, loop, cut, copy, paste and trim audio clips. Bojam also includes a plugin that allows you to record and upload directly into the mix, or you can upload tracks recorded in Garage Band or other software.

One upcoming interesting feature of Bojam’s mixer is the ability to embed a mixing widget in blogs, social networks and websites where users can remix and edit audio from within the embeddable widget. The widget should be rolled out within the next few months

Beyond being a collaborative tool, Bojam is also a community for musicians to find other musicians to play with anywhere in the world, asynchronously. If a song is really good, the musicians can decide to sell it on iTunes or Rhapsody for 99 cents. Music teachers can also use the service to auction off their services (as can studio musicians half-way across the world).

Bojam faces competition from Indaba (covered here) JamGlue, and Minimum Noise (covered here).