Konami/MS
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Metal Gear Solid: Integral

ohh and please release System Shock 1&2 playable in Vista so I can play them for the first time

Definitely System Shock, and the Crusader series.
+1 for Rise of the Triad!!

i've read through some messages and i have to add my votes on
hardwar and homeworld
also, wasn't Deus Ex released free or something?

Lots of repeats, naturally, but hopefully you'll take that as an indicator of how many people are eager to get their hands on a portable, playable copy of these games. Heck, some of these are games I have, but would be willing to repurchase in order to have a more secure backup copy than my increasingly scratched disks or my increasingly old floppies. These are in the order I think of them, not prioritized in any way (though I'm surprised no one else I saw has metioned SSI yet):
BlueByte
Albion
Westwood Studios
Lands of Lore series
Legend of Kyrandia series
New World Computing
Might and Magic series
Access Software
The Tex Murphy series
SSI
Gold Box Series
Buck Rogers series
Menzoberranzan
Stone Prohpet
Dark Sun (wake of the ravager and shattered lands)
Thunderscape
Entomorph
Skyrealms of Jorune
Black Isle/Bioware:
Baldur's Gate series
Planescape: Torment
Icewind Dale series
Sierra, Dynamix, et al
Betrayal At Krondor
Betrayal At Antara
Stellar 7
Quest Series ( Quest for glory, Police Quest, King's Quest, Space Quest, etc)
Gabriel Knight series
Willy Beamish
Looking Glass Studios / Irrational Games
Thief 1 and 2
System Shock 1 and 2
Terra Nova
Ultima Underworld 1 and 2
Origin
Wing Commander series
Ultima series
LucasArts
X-Wing series
Grim Fandango
Every SCUMM game you can get
Bullfrog
Syndicate series
That's a good enough preliminary list, I think.

Just to show support, I'll re-mention some games I'm dying to play again:
Mechwarrior 2 (Seriously the first game to come to mind when I thought about GoG. best mech game ever, great times online as a StarComm in the Shadow Clan)
Earthseige 2
Wing Commander series
X-Wing/Tie Fighter
Gunship 2000 (One of my favorites)
Syndicate series
System Shock 1 & 2
Many old Apogee games like Jill of the Jungle

Good idea.*nod*Already in, go buy it!These are not old! Or at least they're not forgotten by the public yet.*nod*
Also, you reminded me of Flying Heroes, another one I'd like to play.*nod*It was released on Steam. Not for free, I guess, or at least it's the first time I hear that.
But 1NSANE used to be free, by the way. I wonder if Codies terminated the offer because of the GOG.com release.

I would really love to be able to play through System Shock 1 + 2!
Escape from Monkey Island looks like A LOT of fun also, and sadly I've never gotten to play any of these. They simply cannot be found, or just aren't compatible with newer PC's. :(

Freespace II - 5,99 $
Seing Wing Commander running on Vista - priceless :)
When it comes to "modern" games - Adventure Pinball Forgotten Island based on engine of immortal UT

It's alright, but I think most Monkey Island fans, while interested in having it available here, would say that Escape from Monkey Island pales sorely in comparison to any of the other three titles in the series.
Add me in for recommending the Crusader games.
Also, I don't know if anyone has mentioned it yet, but Heroes of Might and Magic I through III would be awesome.

I would definitely purchase:
Any/All possible Star Trek games
Black & White series
Earthsiege series
More Bioware games
I honestly came here hoping that some Star Trek games would be part of the catalog. Even thought it's not, I still hope some will get added. There are a ton of great old games out there though, so hopefully I'll run into some that are enjoyable.

My list of must-haves:
Ultima series (at least 5,6,7 parts 1&2)
Ultima Underworld series
Space Quest series
Planescape: Torment
The Dig
System Shock 1 & 2
Outcast
A "freebies" section would be fantastic. There are numerous games that would qualify for this:
http://en.wikipedia.org/wiki/List_of_commercial_games_released_as_freeware
I know you'll be worried about bandwidth costs but it will flesh out your library and build your community. Also most of them are tiny by comparison to the whoppers up on your service now.
Highlights: Star Control 2 (The Ur-Quan Masters), Beneath a Steel Sky, Elite, Tribes 1&2.

Jazz Jackrabbit series
Commander Keen
Raptor (Shmup)
I remember playing only one episode of these games but they were awesome.

Sorry to be the mature one here. But I doubt you are going to get any DOS games being sold here, because I cannot see how they could guarantee they would work unless they did a deal with DOSBox (a utility that allows you to easily play DOS games in an emulator). It may be difficult legally to charge for a game that only runs because it has a freeware utility included that runs it.
You have to be a clever consumer though, as some of the games mentioned are now freeware, or there is no way to know now who owns the copyright and therefore are considered 'legal abandonware'.
The problem with who has the legal copyright for these old DOS games would make it impossible for G.O.G. to be even able to approach anyone to get permission to sell.
Also, to the person who said they could host free games, well, there are plenty of other sites that do that,, and this is a business. it is no different than Steam, and no one would expect steam to carry free games. In fact, Steam doesn't really do much to any games they sell to make them compatible in the way G.O.G. does. I know of people that bought retro games from Steam and found they couldn't patch them or add mods, etc.
So when listing games you;d like to see,. remember they need to be at least of the win95/98 era (1996+), so the request for the X-Com games are no go (Steam has them), System Shock 1 and 2 is unlikely because the first one is DOS and the second does not have an obvious copyright owner for GOG to approach.
Same goes for the Ultima series and the LucasArts titles, etc. All DOS games.
I would suggest for DOS games you buy via ebay and download DOSBox with one of the user friendly front ends like the D.O.G. front end and get them working on your XP/Vista machine that way. Once you get the handle on DOSBox/D.O.G running these DOS games is quite easy.
As to games like Jagged Alliance (the first one) and the later Gabriel Knight games and the Baldur's Gate/NOX/Icewind Dale/Neverwinter Nights RPG's and other games of that era and later I say 'bring them on....!!!'