Haven't in a while, though I'm planning on running one using the d20 Future and/or Apocalypse rules. However, if I did get a game going, I'd most likely have something based off of classic post-apoc games like Wasteland and Fallout.
Then again, my g/f mentioed she'd be a bit interested in a post-apoc game then had the catastrope occur earlier: say between the late 40's/early 50's to the late 50's/early 60's. Survivors would be running around with earlier-era weapons & gear, & there'd be less of the modern tech or near-future tech that often creeps into these games (like intelligent AI's, cybernetics, etc.). Sounds interesting, though I'm really leaning for a Fallout-like game.