A game designer will often need to model something either as a stand-in for the game or sometimes even as actual final art, depending on the size and composition of the team. In production, designers are often called upon to create level layouts. I am familiar with using Maya, 3DSMax, Photoshop, and UnrealEd as level creation tools as well as for other game production purposes.

Lorrenna Draco (Maya)
Heather Fox (Maya)
Some renders of Kenlow (Maya)
View of the facade of Taurman Mansion (Maya)
A playset modelled from life (3DSMax)
WIP: A room in the keep at Telven of the Falls (UnrealEd + Maya)

Telven of the Falls (Unreal, Maya) All my work except the Abaddon rock texture in the background.
A bridge in Master of Elements (Maya)
Lorrenna Draco (Maya)
Taurman Mansion (Maya) All done with procedural texturing, zero photoshop textures.
Heather's choice: nature or magic? (Maya)
The interior of a cottage (Maya)
A dank boiler room (Maya)