If you like music + software and you haven’t played with the free, Web-based WolframTones, you should. I first saw it several years ago and I’m even more amazed by it now than I was then. As Web apps go, it’s quite brilliant. You can create stunning bits of unpredictable music and then download them or turn them into phone ringtones. It’s deep fun.
Wolfram is Stephen Wolfram, inventor/developer of Mathematica and author of the book A New Kind of Science (which is freely available in a Web version, by the way). WolframTones is based on Web Mathematica.