Music professionals are stuck with horribly archaic and kludgy ways of managing their music and collaborating. We're trying to fix this at Gobbler - building a downloadable, networked application that solves these problems for people who create and work with music. Think Dropbox + Yousendit + Source control - all tailored to work with multi-gigabyte music projects.
We're in closed Beta, but are getting ready for a public launch in the next 6 weeks. All of our work has been done on the downloadable application and the backend, so the actual website is pretty ugly (did I mention we're also looking for a Designer?). But we're using a lot of cool technologies, like MongoDB, Node.js, Redis, etc. And you get to work with a small team of very smart people. Plus, we're very well connected to the music industry - it's pretty amusing getting feedback directly from some of the biggest names in music.