What are the best GOG titles that are NOT on Steam?

Populous: The Beginning

Dungeon Keeper

Planescape Torment

I'm sure there is more, but that's what comes to mind

Neverwinter Nights!

Heroes of Might and Magic 1-3, Nox, and Dungeon Keeper 2.

Gabriel Knight: Sins of the Fathers
Beneath a Steel Sky
Alone in the Dark (1+2+3)

Etherlords 1 and 2, HoMM 3

that one Mafia RTS. goddamn I loved that game.

Theme hospital.

Dungeon keeper 1&2

Fahrenheit

Silent Storm

Tex Murphy Under a Killing Moon, Pandora Directive, and Overseer

HoMM3!

Chronicles of Riddick.

Blitzkrieg Anthology 1 and 2, Dungeonkeeper 1 and 2, Rollercoaster Tychoon 1 and 2, etc...

Master of Orion

Baludr's Gate 1 & 2, Neverwinter Nights 1 & 2, Arcanum of steamworks and magic obscura (preety hard with first contact but marvelous world ), Might & Magic (especially 7 but 8 & 6 are good too), Planescape Torment, IceWind Dale 1 & 2, Heroes of Might and Magic 2 & 3, Total Annihilation, Panzer General 2, Krush'Kill'n'Destroy. Uff I suppose enough ;) and sorry that only RPG's and strategies, I play almost them only ;)