If you haven't heard of "Guitar Heroes", you're probably Amish—which is fine. But if you haven't heard of the open-source Guitar Heroes-style game "Frets on Fire", then you are missing out on the beginnings of what will be a huge story in the coming years.
That story is "interactive music", and I'm pretty sure that it will evolve into an alternative music industry, eventually to mate with and eat the current one, producing a freaky and amazing bastard offspring.
The point is, in Frets on Fire, you can make your own songs, add your own songs, play your own songs. You can give them to other people and they can play them. Other people could "cover" your songs, sample them, remix them, and give them back to you, just like with "real" music, but in video-game format, which makes everything better and more real.
And now (actually for a while now), you can actually create music with the guitar controller that comes with Guitar Hero. There's a band called the Guitar Zeros who have been playing live shows using two guitar controllers and a drum kit (and various computer equipment).
It's only a short step to a version of one of these (types of) games that allows players to improvise (solos!) and be judged on the quality of their improvisations, or to write songs on the fly and be judged on those also. And much more, of course
But the real advantage and interest here is that if musicians can write and create songs and immediately release them to a willing market of gamers, well, I think they'd give major traditional label artists a run for their money. Of course, any indie artist can release stuff about as easy as 1-2-3 as it is, but the market is limited. People are listening to music less and playing video games more. If the two are combined—voila!—a massive new market, and a product really worth paying 99 cents for.
The Guitar Zeros
An interview with the Guitar Zeros