Most of my favorites have already been covered here, so I'm not going to rehash them except to say that A Canticle for Liebowitz and American Gods are two of the finest afternoons I ever spent, and World War Z is well-worth a look... it's an enjoyable and not often-seen track for apocalyptic fiction to take, and given it's open and anecdotal structure it can have as many or as few layers as you decide to read into it.
Most of my recent reads have been re-reads, as the shelves of the local bookshops in my new smalltown home are a little sparse when it comes to my preferred fare. From this month's batch, I'd recommend Random Acts of Senseless Violence by Jack Womack, which , through her diary entries, tells the story of a pre-teen girl's jarring descent from her middle-class lifestyle into her coming-of-age in the ghettos of a near-future America that's (eerily) only a shade or two darker than real life.
Another good one is A History of Knowledge, by Charles Van Doren (anyone here seen the movie Quiz Show? Yeah, that guy). It is, as it suggests, a history of knowledge- a reckoning of the history of human civilization as an account of what our ancestors knew (rightly or wrongly) and when they learned it (or unlearned it). It's perhaps a bit too tightly focused on Western civilization and too informally written (with light spots of subjectivity when the author touches on the ecclesiastical), but the narrative voice is accessible and involving and the information is fascinating and, for the most part, very accurate.
Last but not least are Altered Carbon and Broken Angels by Richard K. Morgan. I've already run long here, so I'll just say "cyberpunk detective noir." Think Blade Runner, aesthetically cleaner but morally much more complex. The key gimmick here is the digitization of the human consciousness, which allows those with the means to switch into different (often enhanced) bodies (or "sleeves") and to be re-sleeved or stored digitally after death. I cannot recommend these two books enough, especially Altered Carbon.