this is one of the most insanely brilliant things i've found to do with youtube so far. basically, the guy asked his friends to each contribute a simple, random piece of music in Bflat. he then uploaded them, compiled them on a single web page and you can mix and match as you please, endlessly if you desire. click on the image and play with it - it does take some time to load everything so you can 'play' it properly, but it's well worth it. brian eno would be proud.