Market Forces by Richard K. Morgan. If you want to run a Car Wars/Autoduel/Shadowrun campaign, this is the book to read. Violent, sometimes coarse, and no happy endings, but to me it perfectly captured exactly what those worlds would have for cultures. If you wanted to create a "street" character (particularly for Shadowrun) this would be an excellent place to get some tips, seeing as how most of us who play RPGs are actually far-off socially from those kind of people in real life.
Fire-Us trilogy by... I forget. Anyway, books for kids/preteens, I think. Concept: kids living alone after a viral holocaust kills just about everyone. The kids range from about 6 or 7, I think, to preteen. Good potential reference for a post-holocaust or Gamma World campaign, because of the kids' distorted memories of what life was like 'before'. My big gripes with the series: the villain felt too cliched/one-dimensional (I couldn't believe in what seemed like a concept rather than a character) and the ending. Let's just put it this way: the kids have been living in Florida for the past five or so years since the viral holocaust, which, okay, that makes sense. Florida has about the most tolerant climate a bunch of parentless kids could hope for - it never gets truly freezing cold - and it's developed enough that the kids can raid stores for several years and still find viable food items on the shelves. But at the end of the series, the kids decide to head north, and all I can see ahead is a lot of frustration and/or death once they leave the subtropical zone. I mean, they may be resourceful, but they're still kids who barely know how to read, much less be self-sufficient past scrounging in abandoned stores and orange groves. Still, for cultural use in a post-holocaust world/game/campaign, this has some useful stuff in it.
Darwin's Blade. Don't remember if I talked about this one before or not, but PASS. I couldn't get past page 100. Bad, bad, bad. The lead character is UberUberOverAlles and the "humor" is recycled ten-year-old Internet "humor". PASS, do not collect $200.