We got off on this topic on the Revolution TV show thread, so thought I'd start a thread here. As of a fan of that show and Jericho, to name two recent TV shows with that theme (and on some level even LOST falls in that category), we started sharing favorite books of that type. Revolution for example is based on one which I haven't read yet, but now will look for--the Emberverse series by S.M. Stirling.
Among my favorites, Lucifer's Hammer, which was made into a movie after I read it. Currently reading and really liking Swan Song by Robert McCammon, even if it has a bit more "religion"/magic than I generally like. I found this while reading a Kindle Amazon review of Lucifer's Hammer (nostalgia trip!), which also recommended King's The Stand, Thomas Disch's The Genocides, and Walter J. Williams' The Rift. I haven't been able to find the last two yet, but I'm looking! There was also a great one, in English but set in France...the main characters are holled up in an old castle type building which allows them to defend themselves from the hoardes fleeing the cities. Sadly I don't recall the name--if anyone recognizes it, let me know. Currently awaiting my eyes on the Kindle is On the Beach...which I realized the other day I'd never read.
I also liked David Brin's The Postman, which I heard about because of the movie...I thought the movie (which was not well reviewed, I think because reviewers then were really down on Kevin Costner) was actually a little better than the book, but the book was good, too.