Call me a puss, but I find this particular song from Minecraft to be particularly beautiful. I just sounds so... Young and innocent, I don't really know how to explain it.
http://www.youtube.com/watch?v=TRcfQFjpKCI
Also, Skyrim's OST was a bit under-appreciated, I think. The game itself was over-appreciated, though... This track here was my favorite.
Non-video game feels:
(Bleed - deadmau5)
(Eminence - Falling Stars)
(Rundfunk - A Dream)
(Ghost Hardware - Burial)