I was thinking you could decide that, for example, Punk = angry, Country = depressed, Folk = relationship misery, Jazz = stoned, etc. By redefining genre tags you don't use to symbolize various moods, you could get the functionality you're looking for. If you already have a Mood tag on your songs, you could sort by that in your tagger to quickly change the genres to your chosen substitutes. Be sure to copy the actual genres into a new user-defined tag so you don't lose them.
Folder browsing instead of using genres for this purpose is more likely to be the right answer, though.
Last edited by happyguy; 06-11-2010 at 12:58 PM.