Mixlr , a sort-of UStream for audio, wants to make it easy for DJs and bands to share and stream live performances to fans. The service, founded by London-based Rob Watson (a recent graduate of the Music Informatics department at the University of Sussex), is currently in a closed beta, although TechCrunch Europe has 200 invites to give away readers. In its current incarnation, Mixlr is a pretty simple offering, although that's partly by design. Comprising of a Mac-only client (although a Windows and iPhone app is planned), users can plug-in any audio feed to their Mac and begin live streaming, pushing out a URL of their feed via Twitter, Facebook and MySpace or to share in other ways. Live performances can also be uploaded, archived, and tagged (including location), as well as sent to a SoundCloud account, a service that Mixlr both complements and potentially competes with.