No game is complete without a fitting soundtrack and we all have our favorites.
Simply just state what made your ears tingle!
In no particular Order:
1) Jet Set Radio
2) Shenmue
3) Final Fantasy VII
4) Elder Scrolls IV: Oblivion
5) F-Zero X
I got loads more i could name but those deserve a particular mention ;)

Hmm. Tough one. I'll try, but in no particular order.
1. Shadow of the Colossus
2. Lost Odyssey
3. Silent Hill 2
4. Command & Conquer: Tiberian Dawn + Sun
5. Guardians Crusade
Was tempted to say Brutal Legend because I know the soundtrack will be amazing, but it hasn't been released yet so I refrained.

My top five, in terms of "best" criteria:
1. Outlaws
2. Deus Ex
3. Ecco the Dolphin
4. Arcus Odyssey
5. Sonic the Hedgehog 3
See attached picture for my video game music collection.

Hmm, I'm not putting these in any order but the 5 ones I listen to the most are
Planescape Torment
Beyond Good & Evil
Tomb Raider
Rome Total War
Halo

Outcast
HoMM3
Planescape : Torment
Dungeon Siege 1
Phantasy Star 3.
Arcus Odyssey is an excellent choice Vagabond.

In no order:
Quake 2
Command & Conquer (the whole series really, as well as anything Klepacki has done, but especially the first one)
Medal of Honor (all of the ones that Giacchino worked on, especially the original)
Shadow of the Colossus
Timesplitters 2

+ 1 to this. Klepacki made some outstanding tracks in his time.
Panzer Dragoon Saga
The Final Fantasy Series
Mass Effect
Outrun

It's probably THE most underrated soundtrack ever. Sooo fantastic.

Why does noone have Tropico?!??!?!

Here are mine (in no particular order)
- Beyond Good and Evil (Christophe Heral)
- Alone in the Dark (Olivier Deriviere)
- Xenogears (Yasunori Mitsuda)
- Final Fantasy series (seriously, I can't decide which one I like the most) (Nobuo Uematsu)
- Rayman (Stephane Bellanger)

Lemme think...
1. Grim Fandango (love that style of music)
2. Fallout 3 (because I like 50's jazz also)
3. Psychonauts
4. The World Ends With You (I dunno why, exactly, since normally I'm not into rap or hip-hop, but somehow the music fit the setting perfectly... and I have such good memories of the game...)
5. Deus Ex (First game. I liked the mix of music styles and the way ambient music merged into combat music...)

I tend not to notice the music mostly because I find if I do then the music doesn't fit what I'm doing... However there are exceptions. I love The Wheel of Time soundtrack.
Karl

Soundtracks I actually still listen to, in no particular order...
Sonic CD (JP)
HOMM IV
Divine Divinity
Streets of Rage
Tales of Legendia

My favourites:
Tomb Raider Legend
Alice
Scrapland
Evil Twin Cyprien's Chronicles
GTA Vice City

-Shadow of the Colossus
-Final Fantasy VIII (the game sucks though)
-Morrowind
-Jet Set Radio
-Super Smash Bros Melee