I have a bunch, so I'm just going to drop them behind spoilers, ok?
"Build That Wall" from Bastion:
Bastion has incredible music and gorgeous art to match it. Seriously, I highly suggest just listening to the soundtrack if you have the chance, maybe while doing busywork or on a long drive or something.
"Apotheosis" from Journey:
This one's very famous, but it's for a reason. The whole game is a celebration of the classic heroic pacing curve- the way stories and music have been composed since ancient Greece, and this song is intended to encompass that. The result is beautiful and well-crafted.
"Of Whips and Strings" (OC Remix of Castlevania):
I haven't played Castlevania, I just love this remix. <3
"Goblin Theme" from World of Warcraft
This song has absolutely no right to be as good as it is. It's so oddly specific, and so much better than anything else in the game. I'm not complaining though.
Video game tracks, eh?
If you want something Silly.
Maybe something Dramatic?
Something a bit Older?
Perhaps a more Chill track?
Or the current one stuck in my Head.
Some songs I enjoy from older games are: Secret Area from Skuljagger Warehouse from Skuljagger Lankus from Darius Twin
I also really enjoy The Legend of Zelda soundtracks but I've always enjoyed the Title Theme from Ocarina of Time and Dragon Roost Island from Wind Waker