You should check out my texture pack:
Broken Anachronism It's a 64x steampunk-apocalyptic themed, but it is really heavy on the apocalyptic aspect.
If that's not your thing, you might like Last Days, which seems to be vaguely based off of fallout 3, but is much darker and dirtier.
The End Is Extremely Nigh is also very good, but it's pre-apocalyptic. It seems to take place in a world where some sort of apocalypse is just beginning, everything looks rather like survival gear and such. It's probably the brightest and least dirty apocalyptic pack i know of, but it's quite good. Overall, it's one of the most well done 32x packs i've seen.
