I just finished World of Goo and I can say without reservation that that game has the best soundtrack of any game yet made. Around 25 songs in total ranging from epic, to haunting, to inspiring, to frenetic, to goofy and lighthearted. Really a masterpiece of video game music composition by Kyle Gabler, the composer.
Edit yeah ... fifteen minutes of research and I still can't embed. Well, here are the links anyway.
Edit #2 - I'm dumb, figured it out. Just quote someone smarter than you and see what they did, duh :/
Menu music:
One of my favorites: Rain Rain Windy Windy
Also, I think Starcraft II does a pretty awesome job of capturing the three races in their themes, particularly this Terran theme (it doesn't really pick up until 30 seconds in):