This site is full of win: Game Music Jukebox. You should really give this a look. More than 120 video game soundtracks. Double Dragon. Marathon. Mass Effect. Hitman: Blood Money. Lots of stuff from 8-bit synth to full symphony scores. And not just the title track, but the full score, broken out by tracks.
Maybe not everything, but definitely a lot and certainly something to tickle your nostalgia fancy. Looks like they update it, too, last one was April 29.
I'm listening to the Metroid Theme now, Brinstar to be exact. IMHO, best score for an 8-bit game ever. I want to make it into a ringtone, I just need to pick the right refrain.
Just saw this on Reddit so, the buffering might be a little slow on some of the larger tracks as people go to it.
Reliver Your Favourite Games Through Music [Game Music Jukebox]