This past week saw the release of GURPS After the End 1: Wastelanders.
It's a toolkit for post-apocalyptic adventurers much in the same line as Dungeon Fantasy 1: Adventurers or Action 1: Heroes or Monster Hunters 1: Champions. It's a prepared set of templates, equipment, and options for a given genre. It's cause-agnostic, though, so if you're thinking "collapse of the oil states" or "zombie virus" or "comet strike" or "radiation that makes mutants" or whatever, you're good here.
I happen to know the "1" isn't aspirational, either - there is a 2 out there in the future. So if you're thinking of going post-apoc, this is a good start.
There are two issues of Pyramid Magazine that can buff this out, too. 3/88 and 3/3 both deal with life after the end times.
Editing later: For a review, check out the one at Gaming Ballistic!