I'm surprised you hadn't done it sooner. Can't say I blame you at all. Aaaaand, what more, google have nice ads. I'd be bothered if it was popups (or ... ugh ... popunders), but google ads are nice and discreet.
Try filefront.com, I've seen people hosting ~4GB of MP3s (trance and whatnot) with it and they had no problems. I don't think they delete your files after a set number of days... There's a 1GB limit per file, so it should be more than enough for the DSPs. :P
First you become an internet "user". Then you learn how annoying ads can be. Later, you are given the chance to make money via ads. Then you circle back to realizing how annoying ads can be once again, if not from experience, but from thought.