You didn't want to get me started on game music ^^
Ar Tonelico 1 and 2 have exceptional sound tracks, and being able to choose japanese voices during gameplay in the US version of 1 is win.
Ar Tonelico 1 (Last Chapter) Ar Tonelico 1 (Scar) Ar Tonelico 2 (Unspoken Feelings) Ar Tonelico 2 (Agni)
The whole Ys series, especially The Oath in Felghana OST
Oath in Felghana (Valestein Castle) Oath in Felghana (Morning Departure)
Tales of series.. Especially Tales of the Abyss.. TOTA has an outstanding OST imo:
Tales of the Abyss (Final Chapter) Tales of the Abyss (The Edge of Decision) Tales of Symphonia (Full Force) Tales of Destiny (PS2) (Last Judgement)
Valkyrie Profile 2 Silmeria.. Another great OST imo:
Valkyrie Profile 2 Silmeria (How Wicked Ruler)
Legend of Legaia 2 - Duel Saga:
Legaia 2 (Wasteland of Far Away Places) Legaia 2 (Advancing to Far Away Places)
Guilty Gear XX (ftmfw)
Guilty Gear XX (Holy Orders)
F-Zero GX
F-Zero GX (Biorex)
And a few others without samples that everyone should know:
- Xenogears OST
- Whole mana series
- Beyond the Beyond
Edit:
Since a few people posted some chip-tune and really oldish ones, here are some of my fav old ones:
Bosconian (Little Wave) Sorcerian (1) Sorcerian (2) Sorcerian (3) One Must Fall 2097 (MOD file) One Must Fall 2097 (MOD file)