General

Square Enix and Nintendo games in general, considering Yoko Shimomura does the composing for a lot of them.

I like these tracks:

Beyond Good and Evil:
http://www.youtube.com/watch?v=jTdcJWDNsao

Persona 3:
http://www.youtube.com/watch?v=8sw96AHqCco
http://www.youtube.com/watch?v=xKsyY7Mnhmg

Persona 4:
http://www.youtube.com/watch?v=_HNvQu9C5qo&feature=related

Chrono Trigger:
http://www.youtube.com/watch?v=g-s-VQBoUdc

I dunno if this counts, but a remix of a song from Sonic the Hedgehog (2006):
http://www.youtube.com/watch?v=-Ne49KtcQlA

Also I like the OST of Okami, Flowers PS3, Hotel Dusk, Tales...I can go and on...haha.

Crystal Chronicles' music is pretty good.

The best OST of any game is found in Tales of Legendia. I can't link one because I'd end up linking the whole soundtrack. Check it out. Seriously.

Kingdom Hearts.
Especially Birth By Sleep.

[url=http://www.youtube.com/watch?v=k-m_9rn8tfs&feature=related]Ventus's Theme[/url]
[url=http://www.youtube.com/watch?v=eRo5kIdgkD0&feature=related]Ventus's Final Boss Theme[/url]
[url=http://www.youtube.com/watch?v=bmgfts2r7kw]Terra's Theme[/url]
[url=http://www.youtube.com/watch?v=iIy85KLfOVU]Riku's is one of my favorites.[/url]

Dude i just like listening to remixes of the classic songs
they are still good themselves though but maybe you get what i mean
[url=http://www.newgrounds.com/audio/listen/334239]example[/url]
they still pretty damn good man
[url=http://www.newgrounds.com/audio/listen/423473]yup[/url]

Castlevania http://www.youtube.com/watch?v=cUCW-7h27u0
@marth211: http://www.youtube.com/watch?v=xsd8cRIQcwU

Castlevania for NES. Heck, most NES and SNES games.

Video Game tracks make up most of my favorite music.

-Saving spot for examples-
[url=http://www.youtube.com/watch?v=hsC1f4_1Z4Y]I would buy a Gamecube to play this game.[/url]

Songs from Guilty Gear or Blazblue are just [b]AMAZING[/b].

Here's some Guilty Gear songs.
http://www.youtube.com/watch?v=sBUWLMbuTgo
http://www.youtube.com/watch?v=jiDguHfPCDU
http://www.youtube.com/watch?v=cABwx29L3ps&feature=related
http://www.youtube.com/watch?v=rGetImTgyFA&feature=related

And here's some Blazblue.
http://www.youtube.com/watch?v=-8MJxlfC1k8
http://www.youtube.com/watch?v=OcyiXDzFDwA&feature=related
http://www.youtube.com/watch?v=xWQdltUMid4&feature=related

@SilverFoxR: That isn't a bad track either. And BlazBlue OTSs are also awesome.
You sir, got a good taste for video game music

[quote=SpadeStyle]As for some old school, here is my favorite track from the Mega Man X series:
[url=http://www.youtube.com/watch?v=GiweKm0eEXQ]Doppler Stage 1[/url][/quote]

I'll trump that one... with MY favourite track from the Megaman X series:
[url=http://www.youtube.com/watch?v=3JA2AUKr758]X2 - Sigma Stages 1 and 2[/url]

As for games with awesome soundtracks... well, first off, howsabout some Blazblue?
[url=http://www.youtube.com/watch?v=xWQdltUMid4]Bullet Dance[/url]
[url=http://www.youtube.com/watch?v=MVwFLsZJzS8]Awakening the Chaos[/url]

Also, the Ys series... Falcom is amazing at making wicked tracks:
[url=http://www.youtube.com/watch?v=i2iW27AqjUY]Release of the Far West Ocean[/url]

[url=http://www.youtube.com/watch?v=i7wPMh_9V0w&feature=related]My favourite.[/url]
Kingdom Hearts has the best Video Game Soundtrack I have ever heard.

Mostly Final Fantasy Games, but specifically Final Fantasy 13. its a bit more hardcore than the rest of the games

Kingdom Hearts also has some pretty good ones.

Kirby games, Zelda games, and Final Fantasy games have the best soundtracks.

[quote=crazygama]this where its at.

[url=http://www.youtube.com/watch?v=78ljfawOKLc&feature=related]makes me cry evertime[/url][/quote]

OMG! Nostaliga is taking over my body again -tears up-

OT:
Mana Khemia's OSTs are one of the best video game OSTs I've ever heard.

[url=http://www.youtube.com/watch?v=1UwEutxA17c]Wind Festival[/url]

This one is from Mana Khemia 2:
[url=http://www.youtube.com/watch?v=lzwfOOc3vas&feature=related]Verethraghna[/url]

As for some old school, here is my favorite track from the Mega Man X series:
[url=http://www.youtube.com/watch?v=GiweKm0eEXQ]Doppler Stage 1[/url]

this where its at.

[url=http://www.youtube.com/watch?v=78ljfawOKLc&feature=related]makes me cry evertime[/url]