I've been perusing Youtube.com recently (like many others right now). Its growing by leaps and bounds and its very interesting. Right now you can find many different music-related videos - from strange home videos involving stravinsky, bowling balls and model cars, to videos of new, Avant-garde minimalist opera. Not to mention the dozens of home videos and art-projects involving the music of philip glass.... you can watch parodies of koyyanisqatsi, babies listening to koyyanisqatsi, some video bloggers awkward reaction to 12 parts... on and on.

On the other end of the spectrum you can watch (and listen) to performances of debussy, ravel, beethoven, bach, etc, by students and professional musicians. Its a great resource if you're wanting a concert but dont have the time. I think i could spend far too much time on youtube.