I posted this in your other thread, but will post it here too for others.
http://dig.ccmixter.org/
Search for tracks that use Creative Commons license. Make sure to filter the right attributions relevant to you.
http://www.youtube.com/teknoaxe
http://www.youtube.com/user/MMMontageMusic/videos
Music fit for YT videos (montages, updates/vlogs, etc). I'm not sure about other uses, but the creators are usually pretty understanding.