weka is an interesting looking Java enviroment to explore machine learning. There is a weka book available.
I'm learning this because you can do some neat analysis of music with a combination of Marsyas and Weka. Marsyas is a program by Dr. George Tzanetakis to do analysis of audio. It's really neat.
It's really cool that I'm involved in this project, because for years I've wanted to apply Genetic Algorithms to analyzing music, to help decompose a song into all it's constituent bits. I even had written up some code in C and called it "betabeat", but never got it into a state where it was ready for public consumption. Now, I think I'm going to try it again with the Marsyas libraries.
