Speaking of good erotica set in the apocalypse, I would be remiss in not mentioning Maxine of the Wasteland by Callista Hawkes. Hawkes writes a lot of great interactive fiction and this traditional novel is pretty great too.
The heroine, Maxine, comes across a man dying in the dessert. His heart rate drops dangerously low so to save this stranger’s life, she blows him. I’m no doctor, but the movie, Crank, taught me this is a legit way to keep a man’s heart rate up. This just the first of many encounters in the wasteland that involves guns, cars, bartering, bandits and lots and lots of sex.
I liked this book a lot and it scratched that Mad Max With Porn itch that is so rare in erotica.