every once in awhile I'll listen to some music from a game i've never played. I've gotten into the habit of checking the OCR front page for new music, and when I find something totally awesome, I'll check out the source tune and (in some rare cases), I'll end up playing a game based off a few songs/remixes I really liked.
I also have that nostalgia connection thing where I don't want to listen to the music if I haven't played the game, but I'm trying to break that. I've been paying attention to artists/composers that have a reputation for making good music and I'll go seek their discography to see if whatever else they've made is good and that will always give me music from games i've never played...it's really hit or miss, but i've heard some really awesome stuff getting music this way