There are so many great and inspiring images on Deviantart.com, but they're a bit difficult to link directly. Here's just a few things I came across of interest in a quick search or two:
Red Dawn: Beautiful!
Environment: Post-Apocalypse
In Sight of Apocalypse
Suburban Apocalypse: Nice mixed media
Last Man Standing
World War III: Featuring a sniper babe and a mushroom cloud
The Final Day
Apocalypse: A Nice landscape
Nuclear Wasteland: A bleak winter or nuclear winter landscape.
End Times: Ruined cityscape
Soviet Apocalypse: Moody Soviet submarine exterior