Any list of great video game soundtrack list that does not include THPS is bunk. Tony Hawk is measurably one of the coolest people to ever walk the Earth and this soundtrack wins.
Halo and the Gregorian chant thing. Chills. Halo 3 might be better, tho.
Space Harrier. Meant to be played at a motion-enhanced sit-down machine.
If Tony Hawk is he coolest guy ever in a video game, Parappa is a close second.