surprised i haven't seen much reference to Tim Follin's work! IMO the title screen music from Plok! is unquestionably the most impressive bit of sound i've ever heard from a SNES. just when you've picked your jaw off the floor from the amazingly convincing harmonica sound, the lead "guitar" kicks in and your jaw drops again.
for a bit of a more conventional chiptune sound, the NES Pictionary soundtrack (also Tim Follin) hits pretty damn hard considering that it is, well, Pictionary