As The World Dies is definately the gold standard of zombie literature, the final installment of the trilogy is supposed to be out next month. Really great memories, logging onto the old site to find a new chapter up, just amazing writing.
Aside from that, I recently read one called Pariah by Bob Fingerman. It actually doesn't have a lot of zombie action, focusing more on the characters trapped in an apartment building, but a really great story.
David Wellington's zombie trilogy, Monster Island, Monster Nation, Monster Planet. The first one was the best, but the other two aren't bad.
Xombies, by Walter Greatshell. It also has a sequel, but I didn't like that one as much.
The Rising and City Of The Dead, by Brian Keene. These aren't traditional zombies, but demons possessing dead bodies.
Dead Sea, also by Brian Keene, these are more traditional type zombies.
Dead City, by Joe McKinney. Pretty good story, it also has a couple of sequels, but I haven't read them yet.
Deathbringer, by Bryan Smith. Kind of a different zombie story, but pretty good.
That's the ones I can think of off the top of my head.