Neato! I never knew about some of these:

play_last > daysago(5)
Finds all the tunes that have been played in the last 5 days

refs > 3 and not (tracknr = 2)
Finds all tunes that have a reference count greater than 3 and whose track number does not equal 2.

dirty = "true"
Finds all tunes or playlists that are marked dirty

Are some of these jemplode only?