What about a field for artist and one for album artist?
For instance, say I have a Fats Waller CD. He's the album artist. But then say the song is a Fats Waller/Jack Teagarden tune - that'd be the artist.
This is a none compilation example, but should work for complilations too. Compilation CDs are the one thing that drives me crazy when I rip my CDs to my PC.