I know there have been a few threads like this already, but to the best of my knowledge, there hasn't been a general, end all one. Until now.

I'd like to kick it off with my top 75 favorite tracks. Why top 75? Because I like to go 65 steps beyond. I picked these mostly based on there stand-alone value, but I did consider things like how they were used in the context of the game as well. If they made the game that much more awesome, I ranked them higher. I also tried to add in less well-known ones, because if there's one thing that makes a list boring, it's being something everyone's seen already. Also note that I haven't played all the games that these tracks are from.

And feel free to post your favorites. I haven't had the luck to hear all the awesome music video games have to offer, so many good games aren't included on the list (sorry, Final Fantasy fans). All the more reason to post it yourself.

I'm way too tired to post an enormous list.
I'll throw some up and add more to it tomorrow, when I have the patience to search all this crap.

YouTube - Klaymen's Theme
YouTube - Iji - Tor - (Tors theme)
YouTube - Chrono Trigger OST - To Far Away Times ~ Ending Theme
YouTube - Shadow of the Colossus - Final Battle
YouTube - Aquaria OST - Undiscovered Waters (Open Waters III)
YouTube - Dancing Mad (Full Song) - FFVI
YouTube - Luna Ascension - Tower of Heaven
YouTube - Scott Pilgrim Medley - Scott Pilgrim vs The World

In no particular order...

Phoenix Wright - Cornered (Variation)
Mario 64 - Jolly Roger Bay
Tower of Heaven - Pillars of Creation
Donkey Kong Country 2 - Stickerbrush Symphony
MM8BDM - CTFMUS3
Mario Galaxy - Gusty Garden
Mario Galaxy - Buoy Base
MM2 - Wily Stage 1
Cave Story - Moonsong
DDR SuperNOVA - Red Zone
Star Fox - Corneria
Twilight Princess - Sacred Grove
Super Mario RPG - Beware the Forest Mushrooms

YouTube - Legend of Zelda Super Epic Medley Made in Mario Paint Composer
Best song ever, hooves down.

.hack//G.U. (The dot hack games have so many good songs...)
YouTube - Dot Hack//G.U O.S.T 2 - Desktop
YouTube - .hack-welcome to the world/gentle hands

Katamari Damacy:
YouTube - Katamari Damacy OST, T12: Que Sera, Sera
YouTube - Katamari Damacy Soundtrack - 05 - Lonely Rolling Star
http://www.youtube.com/watch?v=hR7nX76eRiI

Silent Hill (I like most SH songs, but here are some favorites:
YouTube - Silent Hill 3 - Letters From The Lost Day
YouTube - Silent Hill Room of Angels Vid with lyrics
YouTube - Silent Hill 2 Soundtrack - True.

The World Ends With You (also love all these songs):
YouTube - Calling - The World Ends With You Soundtrack
YouTube - The World Ends With You- Déjà Vu (Full)
YouTube - It's a Wonderful World/The World Ends With You-Twister
YouTube - The World Ends With You- Three Minutes Clapping (Full)

The lists go on, and on, and on...

I realy love the Super Mario Galaxy music xD

Super Mario Galaxy 2 - Yoshi Star Galaxy!

LTTP - Dark World Theme
Yoshi's Island - Giant Bowser
Professor Layton - Layton's Theme

Yeah, I went kinda crazy making that list. It's something I've always wanted to make, but it took more effort than I thought it would. If I had known how long it would take to link all those songs I probably wouldn't have bothered.

My Video Game Music List
Lets hear all that song.

And many more.