Plenty of things here that I like, but here's something no one else has mentioned yet: Bastila Shan's theme from KotOR 1.
[youtube]zeoGAKXsMjE[/youtube]
It fits the scenes in which it plays wonderfully, and it strikes a balance between departing totally from the music of the movies and being lifted directly from them.
Also, the main theme from Persona 3, "Burn My Dread". It's an awesome song, despite the horribly butchered English pronunciation.
[youtube]RbsAyGQ0k_U[/youtube]