Most underrated videogame OST's

[Black Mage]

Conker's Bad Fur Day

God, that games was hilariously awesome.

Rock Solid

[Triad Orion]

So after watching this video, I've come to realize that Sonic 1 for the Sega Master System and Game Gear has a pretty boss soundtrack that has no recognition whatsoever.

I mean, how

Actually, I remember playing this game a lot as a kid. And really, I think this soundtrack does really have a lot of potential for remixing. And it was still pretty badass for a Game Gear's limited sound capabilities.

[SoloGamer]

The 8-bit Sonics have some pretty good tracks from what I remember, some of which were reused in latter releases. Unfortunately, they're often overlooked in favor of their 16-bit brethren.

[Flare4War]

Bless anyone and everyone who mentioned Brainlord and Blast Corps.

[lazygecko]

The first two 8-bit Sonic games were scored by Yuzo Koshiro.

The soundtrack to the late 16-bit gen Disney game Maui Mallard was scored by Michael Giacchino, who later went on to do the music for Lost.

[The Damned]

What? No Golden Sun?

For shame. They used that pan pipe to great effect throughout the entire series.

[The Coop]

Having now beaten the first game in the trilogy, and knowing how beaten and battered this game was in reviews, I get the feeling The Legend of Spyro: A New Beginning's soundtrack didn't get as much love as it should have. There are some really beautiful orchestral/synth orchestral pieces in it, a few of which would fit right into a Tim Burton film like "Sleepy Hollow"...

Credits theme

(it's the only version I could find on YouTube, and the last ten seconds are missing for some reason)

There are also dramatic, battle-esque themes, but those are two that stood out to me as I played it.

[TheHands]

ScribbleNauts has a pretty good OST, most folks overlook it because the main themes come back in most other songs (like Katamari music does).

I also agree with RETROMAN about ESWAT. That game was fun.

Quake, as made awesome by Trent Reznor, is also often overlooked.