I HATE games that are all Techn, they need to creat a mood for the level you’re on
More votes for Castlevania (I’ve got a great techno mix of the theme in my MP3 player right now.) the Gabriel Knight games (#1 was great, but let’s not forget the great Schloss Ritter music from #2–not to mention the opera at the end!) and The 7th Guest (In my mind, I am grooving to the strolling-around-ambient-sound music that went ba ba-ba ba-ba-ba ba BA ba ba ba ba ba and then there was a rest and then a few clicks and then the piano bit. You know what I mean.)
Well, I’ve always been partial to the music in Maxis’ “Sim City 2000”. Very jazzy.
And there’s a game called “Nightmare Creatures” on the N64 that had some neat original music…Though, as I understand, there’s an updated (Playstation?) version with music by Rob Zombie…Which, cool as it may or may not be, I can’t see as keeping with the Young Sherlock Holmes-ey music.
And, of course, there’s “Maniac Mansion.” 
Ranchoth
“Don’t be a tuna head.”
Let me just start off by spouting stats – I’ve got almost 400 video-game music MP3s on my computer, which constitutes about 3/4ths of my total music collection. It’d be bigger, but I only keep the tracks I really like. When I feel like wasting money, I’ll go and buy expensive imported Japanese video-game soundtrack CDs and add 'em to my collection. I don’t suppose there’s any interest in trading/sharing this stuff?
Anyway… choosing “best videogame music” is kind of tough these days, since so many tunes are just regular songs that have been licensed by the companies (examples: Crazy Taxi, WipeOut XL). Role-playing games traditionally have been big on classical music, but IMO that’s a bit of a cop-out, since classical music is not too hard to do wrong. Similarly, a lot of games tend to go for techno/electronica tracks these days, and while they’re also neat, it’s also something that’s relatively easy, IMO.
With that in mind, let me make a few nominations that (mostly) haven’t been mentioned yet:
[ul]
[li]“Splash Wave,” from Sega’s Outrun video game. Fast-n-easy pop/rock, with an infectious beat.[/li][li]The title theme from Lucasarts’ Sam and Max Hit The Road, for a nice lighthearted jazz number that captures the “gumshoe attitude” of the game.[/li][li]The background music for the “Chemical Plant Zone” from Sonic the Hedgehog 2. Short, but really sticks in your mind, especially the horns.[/li][li]Most of the tracks from Taito’s The Ninjawarriors Return for the Super Nintendo game system. Each one is a fairly long loop, with a great “heroic endeavor” feel that fits the game.[/li][li]The title music to the Atari Lynx version of Klax. A thumb-slapping pop-rock theme that definitely needs stereo headphones to be appreciated.[/li][li]The ending credits to Nintendo’s Starfox for the SNES. Yeah, it’s a John Williams-wannabe orchestral piece, but it’s a damn good John Williams-wannabe orchestral piece.[/li][li]The title theme to Electronic Arts’ original Archon computer game. The opening cascade alone is enough to bring back memories.[/li][li]Finally, just about anything from Sonic R for the Sega Saturn. Great pop music, nice bubblegum-pop love-song lyrics, and awesome singing.[/li][/ul]
I could go on and on, but I think I’ve geeked out enough already… 
Selected songs from the KJAH or Game fm radiostations in Grand Theft Auto 3.
(because we give it all that we GAAAAAAT!! )
The final boss music for Sonic Adventure is the best I’ve ever heard. It sets the pace quite nicely.
Now if I could only remember the words. I have the instrumental version stuck in my head.
Uniracers (SNES) also had some pretty nice music. Well it fit my tastes, anyways.
I have a cassette tape (you remember those, right?) 
that has DKC tunes on it. It was released before the game, IIRC. No! Not more music to get stuck in my head! Argh!..
Well, as far as fairly recent games go, There have only been two games that I have enjoyed the music well enough to allow it to play in the background constantly. For me, background music has to be subtle, catchy, and not me screechy or noisy.
the two games are:
MediEvil for Playstation and
American McGee’s Alice.
I’ve always had a fondness for the main theme to Final Fantasy IV, although the rest of the series has some quality work. Lately I’ve also had the music from both Vigilante 8s and GTA2 rattling in my head.
Nobody’s mentioned Final Fantasy Tactics or it sucessor by the same musicians, Vagrant Story? There are plenty of good games with decent rock soundtracks, but very few pull of successful orchestral/classical pieces like the above two.
And I second Netbrian’s nomination for Y’s. The music in the games themselves are remarkable: they were among the first CD-ROM video games ever made, and the audio was terrific. The music was so good, in fact, that like Netbrian said, there are whole CDs of just remixes: vocal collections, piano arrangements, orchestral arrangements (I have one by the London Philharmonic!) and jazz/funk remixes. Zounds!
BTW, I think the music from FF3 is completely overrated. Sure, the cheesy opera made us laugh, but good music? Pshaw.
There are quite a few games that have music that I really like.
My favoritres, though, are The Longest Journey’s soundtrack, and that of Little Big Adventure (aka Relentless in the US).
The music in TLJ is always incredibly appropriate for what’s going on, and I like it just for what it is.
The music in LBA is just beautiful.
-Disciple of Alf
there was this moon game on Atari that had awesome tunes.
bleep bleep bleep bleep boink bleep bleep boink boink bleep bleep bleep bleep
wipeout and the up and coming wipeout fusion
Interstate '76
Jet Grind Radio was awesome, so was Diablo and Red Alert.
if you were curious, the greatest video game composer of all time is the legendary koji kondo, probably most famous for the super mario bros. music, but he has done plenty of other stuff, too. just thought i would mention it since video game composers don’t get a lot of attention.
Most of my favorites have been mentioned - Streets of Rage, Parrapa, Jet Grind Radio, Spy Hunter…
Here’s an obscure one - does anyone remember the loading music for Ghouls for the BBC Micro? Not really great, but cool, and it got louder and louder as you watched the game load. Desert Strike on the Genesis/Megadrive had some cool music (for the time) that rocked when in attract mode… I think that was rob hubbard too.
Only because that music is running in a constant background loop in my head anyway so I didn’t think of it. The “choose your party” music is as ingrained in my head as “Happy Birthday” at this point.
I finally found the soundtrack at a CD store in Japantown in San Francisco and paid an embarrassing amount for it. It’s not quite the same without all the little screams, though…
Assuming you weren’t trying to be funny, I believe you’re talking about Moon Patrol, the port of the Williams arcade game. Definitely a goofy and bouncy tune there.
My favorites:
-“One Winged Angel”, the orchestral/choral piece that plays over the final Sepiroth battle in “Final Fantasy 7”
-The Zelda stage in “Super Smash Brothers”
-Sonic the Hedgehog 2-“Aquatic Ruin Zone”
=An obscure Playstation game “Critical Depth” has an excellent soundtrack.
Gran Turismo has a killer soundtrack. Garbage, Feeder, etc. If I ever bought a Nissan Silvia (which is about the only GT-calibre car I could afford), I would have to get a copy of the GT soundtrack to play whilst driving it.
‘if flesh could crawl my skin would fall right off my bones and run away from here … far from God … as heaven is wide …’
Whilst the soundtrack for GT2 was kinda poxy in comparison, some of the music played in the background on selection screens are classics! That cheesy pipe organ piece that plays in the background when you bring the Licence Test selection screen up is a classic example.
I digged the vast majority of the music used in Final Fantasy VII. It was groovy and set the mood very well.