I don't see any reason that separate off topic posts can't exist. Like anything they'll eventually sink to the bottom when they've run their course.
As far as soundtracks go, assuming we skip music games like DDR or GH, it really depends on what you grew up with.
Zelda, Mario (1, 2, and 3), Ninja Giaden, Master Blaster, etc all are highly recognizable and appreciated by myself because of the time I spent with those games.
Mario 64 gets special notice for technical accomplishment. Some levels had multiple, similar tracks that would crossfade back and forth depending on what/where Mario was/was doing. It was most noticeable on the level with the pirate ship, when you dove into the water.
The Need for Speed games have had great music too.
But my favorite is probably the original Doom soundtrack. Classic.
