The NES version of the Toaplan shmup Flying Shark/Sky Shark has an amazing soundtrack. The theme of the first stage is notable because it starts with the original arcade stage 1 theme, then it segues into the typical Tim Follin composition style.
Tim's work on the NES title Target: Renegade is stellar, and quite complex for the time.
Gotta give some credit to therestofthe soundtrack as well. A trick Follin used in some of his SNES tracks was to take chords and use them as samples, in order to fit more notes into a single channel. Apart from the title theme, Plok's entire soundtrack only uses up five of a possible eight sound channels, meaning that the sound can do whatever it wants in the other three without cutting into the music. It's worth pulling the channels apart in an emulator to see how this stuff's done.
Ken Griffey Jr.'s Major League Baseball deserves special notice for being a first-party Nintendo title with music by Tim Follin. (Ironically enough, it was never released in Follin's own homeland— baseball's not all that popular in England...)
Super Off Road for SNES, one of the Follins' earlier SNES soundtracks, still manages to push the sound chip to its limits even in its first couple years.
One of the really rare examples of Follin brothers giving an A+ soundtrack to a good game (a licensed game, moreover; cos' it should be noted that not all licensed games are bad), apart from Rock 'n Roll Racing listed above, is Tom & Jerry (and Tuffy). Technically, it's nothing else than a potpourri made of the score of Puss Gets the Boot episode, but, oddly enough, it fits the game like nothing else.
Sega Genesis/Mega Drive
Time Trax contained Follin's only soundtrack for the Sega Megadrive. Unfortunately the game was never released.
As well as the familiar 3-channel square wave output which should be familiar to any 8-bit veterans, the ZX Spectrum also had a 1-bit piezo speaker built into the hardware. Using some specially coded drivers, and some insidious form of witchcraft, Mr. Follin was entirely capable of churning out some surprisingly complex multichannel pieces, such as those heard in Future Games, Chronos, and Raw Recruit.