The "Game Wish List" is overwhelming. There are lots of really useful suggestions in there, but many people are also asking GOG to release games that are already for sale on Steam.
The catalogue is still a bit limited, and it would be great to mention titles that were actually released by the companies already working with GOG. I suggest two:
Interplay: Blackthorne
Codemasters: Severance: Blade of Darkness

For interplay two I'd like to see:
Battlechess -whichever version is considered "definitive", I only played the dos disk copy).
Star Trek 25th Anniversary / Judgment Rites - These two are great (especially the 2nd) and need some more loving. It would be nice to see the speech-enabled versions too, as they are tough to find.

Blood & Magic !!!

Planescape: Torment.

I didn't list it because due to rights issues we'll probably never see it. :(

Something to do with Wizards deciding not to sell anything in the planescape setting. It's an AD&D game after all. There was a post about it not long ago. That kind of annoys me, as I don't understand why you wouldn't agree to have a best selling PC RPG back on the "shelves". It's like free money - just take it and shut up. ;)

Someone made a mistake, because Planescape has nothing at all to do with Sierra. It's a Black Isle game (past development studio for Interplay), published (of course) by Interplay.

Many people want these games without the heavy steam application. That thing is a resource hog. Plus there have been reports of GoG installers working on older OS's and even under emulation on non-windows machines. Steam checks for OS versions and thus won't even install on older windows machines, and emulation with steam is pretty difficult. I got it to work a couple of times under transgamings cedega, but it was still pretty rough from a noobs point of view.
The GoG installer is much more convienent.

I can't believe none of you thought of The Bard's Tale - one of the greatest RPGs of all time :) (that is, in my rather not so humble opinion)
Mind you, it was published by EA, but developed by Interplay, so I think it still counts.

I don't know why it says Sierra, as they have nothing to do with it. Unless VUgames somehow bought the license and put it up there. However I doubt it, given the '1999' date.
Also gametap is vastly different than selling the game. Although who knows, maybe they'll change their minds.

Are you sure it regards also old games?
An official response? I want desperately to play Torment -.-