I remember talking to a a few people about 6 months ago, one of whom was connected with Musicbrainz which, I suppose is the closest equivalent to IMDB.
I wondered out loud if you couldn't use the data from Musicbrainz, combine it with Amazon and The Covers Project, maybe use a Web search API to find pages that say "Official" or "Fansite" and then sling it all together.
Is that going to fill in Band Members, Trivia, Producer or whatever? No. But it will get a good framework for sticking that stuff in - it will get you Bands, Albums, Tracks, Covers, Singles, Labels, Album Art and related Bands. Other people would fill in the none automatic stuff and fix any bogus data.
Of course I just want it for the trivia. I love the trivia, me.