Most people don't know Steve Reich, but they should. Especially since he just won himself a Pulitzer. He's one of those super-cool minimalist composer types. What's a minimalist? A composer who specializes in making an entire piece out of two notes. Basically. If you've seen The Hours, you've already had an earful of Philip Glass (although he claims he's not a minimalist). I won't go into the whole debate with minimalism (you should know that there are always debates in music - - on EVERYTHING), but the gist of it is that some people like it, and some don't. I think it's pretty freaking cool. Especially with Steve Reich.
A lot of what he's known for is tape loops and phasing. I can't really explain it; you'll just have to listen. Here's his grammy-award winning "Different Trains":
"Piano Phase" is also really nifty:
A search for "Double Sextet," his Pulitzer masterpiece, yields these: