There is a new band out there, BL8ant, making short music clips they call "SongMentary's" (Song + Commentary) that allows video bloggers, as well as musicians to improvise over their music beds.
A video blogger, YouTube enthusiast, or band would use these short music clips (free) as a background to their video. Also, it adds a dimension to the web not yet made popular. Bigger than a "ringtone" but shorter than a "song", one could blurb out their words over the background, thus making a short song.
Anything from "I hate Mary", "Look what they've done, them damn terrorists", to "I love Polina". The music beds are there, the user supplies the words, the meaning, and perhaps the hit song...
Check Out BL8ant Band at Reverbnation
Link: www.ReverbNation.com/bl8ant