I was searching for something along the lines of what you're looking for a while back - an archive of samples used, or something similar.

I found this website - http://the-breaks.com/. Now, of course, it's far from definitive, but there's a lot of information on there. It only deals with hip-hop/rap songs (i.e. hip-hop/rap artists that have sampled other music), but as a starting point it's not a bad reference.

Further recommended browsing would be in the forum - if you need something specific which isn't within the lists in the navigation pane, it's probably worth asking for it. The people there seem to have a wealth of knowledge between them.

EDIT: Just looking around again, there are actually non-urban artist listings as well. For example, in the "Film" sub-section, there's some Manic Street Preacher songs cited that have sampled film quotes.