my normal pattern is to organize albums like this, within folders named after the corresponding artist (showing the first few entries from my Björk folder)
compilations go in a Various Artists folder
soundtracks go in a Soundtracks folder
i also make generous use of tags, and of the incredible flexibililty of foobar.
for compilations i fill %album artist% with just Various Artists, and i fill %artist% with the track's artists.
soundtracks are done similarily, but %album artist% is set Soundtrack simply so that all my soundtracks show up in the same place. then for the %release type% tag, i put either Soundtrack or Score.
in foobar, mixed-artist albums show up like this:
when i throw music on my ipod however, i replace %artist% with %album artist% to avoid apple's horrible implementation of compilation albums.
here is a screenshot of the end result:
