Where to find out every version of a release?

[braaaaaaaapp]

Alright, so kind of a random question, but does anyone know where or how you can find all versions of a certain movie or cd release? For example, when a cd is released, certain stores get certain exclusive features, such as bonus tracks, remixes, videos, or whatever else could come with it. Same goes for movies where some come with bonus discs or special packaging or whatever. Anyone know where you can find out where everything is being released without searching at every single store and website?

[aminorthreat55]

DVD Beaver is badass for movies, although not purely what you're looking for.

[braaaaaaaapp]

Never heard of DVD beaver but I'm fascinated with the name haha. I'll check it out, thanks.