"The Road" is nothing short of brilliant, Mike. Totally deserving of its Pulitzer, and Cormac McCarthy is a genius. Expect the film adaptation, starring Viggo Mortensen, sometime in Nov. 2009.
Other post apocalyptic and post-disaster books I'm a proud owner of are:
"Alas, Babylon", by Pat Frank (survivors after a nuclear war between the US/USSR)
"I Am Legend", Richard Matheson; No doubt you've seen at least one of the movie adaptations, but the novel goes into great detail how the hero has equipped himself and set up his home to stay alive, and also recounts how he starts to lose it from isolation and alcohol abuse.
"Blood's A Rover", "A Boy and His Dog", and "I Have No Mouth, and I Must Scream" by Harlan Ellison; Basically look for a big collection of Ellison's short stories to find these, these short stories should all be packed in there with many others. "I Must Scream" deals with the last four human beings alive on earth, held hostage against their will by a sentient and vengeful supercomputer.
"Wastelands: Stories of the Apocalypse" - ed. by John Joseph Adams - This is a collection of short stories in the post-apocalyptic genre, all of which are very well-written. One is tongue-in-cheek and light-hearted, with the last line reading, "Will the last person on the planet please turn out the lights?"
These aren't fitting into the categories you want but I also recommend "No Surrender: My Thirty Year War", by Hiroo Onoda and "An Island to Oneself" by Tom Neale.