http://beaterator.rockstargames.com/beaterator.html
http://www.ampledesign.co.uk/va/
There's also this collaboration site: http://www.kongregate.com/collabs
For more ideas, have a look through CDM: http://createdigitalmusic.com/
You can start by borrowing music from other games and put an announcement (on forums, mailing lists, in game) saying that you need music. If people like your game somebody with musical skills will help you creating soundtracks eventually. Just don't expect this to happen overnight. NAEV has been under development for over 6 years.
it also mentions a book that presumably discusses the algorithms. book: http://mitpress.mit.edu/catalog/item/?ttype=2&tid=10661