These are all free by the distributors! Enjoy!
-Portal 2 OST Vol.1 "Songs To Test By": http://www.thinkwithportals.com/music.php
-Silent Hill 2 Complete OST: http://downloads.khinsider.com/game-soundtracks/album/silent-hill-2-complete
-Shadow Of The Colossus OST: http://downloads.khinsider.com/game-soundtracks/album/shadow-of-the-colossus-ost
These are the ones I've had on loop in my iTunes library for days now! Hope you enjoy them as much as I do.:)