Gain Ground SX, Double Dragon II, Fray, Kiadan 00 (sp?)
Gain Ground is even more fun than I remembered it to be, plus it has excellent music that really fits each stage.
I don't know what to think of Fray (piece of crap or easy joyride?), and Kiadan 00 seems like it might have potential, even though it initially doesn't grab you by the balls, so to speak.
Double Dragon II -- just confirming that the music complements each stage. It does.