I sometimes think I like videogame OSTs more than videogames.
Here are just 3 quite different examples of VGM I love:
Okami (full OST, almost every tune is beautiful) http://m.youtube.com/watch?v=84ZPfdCsmmo
(I imported the gorgeous 5 CD set from Japan; the YT upload is not from me btw)
Annul (from HL2 mod NeoTokyo) http://m.youtube.com/watch?v=oM6eZJRurFk
(full OST or single tracks can be bought here: http://edharrison.bandcamp.com )
Crashed Ship Fregate Orpheon (from Metroid Prime): http://m.youtube.com/watch?v=QN5IrH9Fkxk
Best VGM related youtube channel imo: http://m.youtube.com/user/RoeBlogThing