Best soundtracks of all time: Bastion and Transistor, both by Darren Korb. Bastion has 3 songs with lyrics, Transistor has 4, but 5 of those are sung by Ashley Barrett, who has a heavenly voice. I'm not quite sure where to get the Bastion one, mine came with the Humble Bundle a few years back, Transistor's can be bought on Steam and includes hummed versions of all the songs (has to do with an in-game mechanic, you pause time to set up your turn's action, the song becomes muffled and the main character hums softly along to it).
Also: Skullgirls soundtrack. Can be bought online, too.