I have fond memories of a distant past trying my hand at the original Fallout game, with its unique aesthetic bound into a post apocalyptic world. Fallout 2 was much lorded as well and the anticipation of number 3 (building upon the Oblivion's Gemebryo Engine) is high.
[Adam Adamowocz concept art for Fallout 3 from the main site - shrunk for inclusion here]
The game will be out shortly, but for now it is the concept art that has me most inspired. The work is by Adam Adamowicz and the released artwork shows a really nifty suite of explorations into how the world and its aesthetics work. Adam's diary entry on the Fallout site is a great look into how he set about designing the elements that make up this world. There is also the article on the design of the Pip-Boy 3000 by Istvan Pely featuring Adam's art.
The amazing paintings also available on the Concept Art pages of the Fallout site show a world torn apart, ravaged by the nuclear holocaust. I am not sure if this work is also Adam's though...
[Fallout 3 concept art paintings on the official site]