Idk why, but Hollow Bastion's ost from Kingdom Hearts always fills me with a sense of wonder and mystery. It's beautiful music.
This theme always got my blood pumping, particularly because it's played while fighitng one of the game's 2 superbosses(yes, this game has 2 superbosses.) This superboss is nearly impossible to stun, and at will can use almost every attack from the arsenal of ALL your characters, including their Mystic Artes(ultimate attacks). Oh, and he's got a ridiculously high 120,000HP(the final boss has only 60,000) which becomes an obscene 240,000 at the highest difficulty.
And as a bonus, here's a remix I found of that theme.
A lot of music in games I dunno, I just stop doing stuff as if it stopped time and I'm thinking real hard about nothing and everything, it's a weird feeling. Sometime I even want to cry and I don't know why because it's not particularly sad or joyful. Main examples would be Zelda games, Final Fantasy games, Kingdom Hearts, etc.
Recently it's Suikoden:
Poignant but kickass~!
I'd have to say Persona 4's OST has had like the biggest impact on my day to day life. Can't help but hum this or have it playing in my head on rainy/cloudy days.
Same with this one on bright, sunny days: