Keene, Brian The Rising
Keene, Brian City of the Dead
End by zombie and pretty good too.
Not a typical zombie book though. In these the dead bodies are possessed by things from another dimension and like to make wise cracks while trying to get to your tasty flesh.
Moody, David Autumn
Moody, David Autumn: The City
Moody, David Autumn: Purification
Zombie again. Not as good as Keene's but you can get the first one free.
Free is good
Stirling, S. M. Dies the Fire
Stirling, S. M. The Protector's War
Stirling, S. M. A Meeting at Corvallis
All modern tech just stops working; electricity, combustion, firearms, etc. They are okay but not great and not really what you are looking for. #4 is out but I haven't gotten around to reading it yet.
Bosse, Malcolm Mister Touch
Its been a long time since I read that one but I liked it. Its an end by virus book.
Brooks, Max World War Z
Everybody has already posted that one. Its ok but its setup after the zombie horde has pretty well been taken out and is more of a documentary.
Dickson, Gordon Wolf and Iron
Griffin, Russell Century's End
Herbert, James Portent
End by nature going nutty. Didn't really like that one.
Hodge, Brian Dark Advent
Can't remember this one but my list shows that I liked it

. Its a death by plauge.
Koontz, Dean The Taking
Weird one that I can't really say much about without giving it away. Not all that great.
Matheson, Richard I am Legend
Sure most people know that one. Not one of my favorites but lots of other people seem to really love it.
McCammon, Robert Swan Song
Damn good one. If you liked The Stand you will like this one. This one is end by nuclear war.
Nevil & Pournelle Lucifer's Hammer
Another really good one. Comet hits the Earth.
Robertson, Pat The End of the Age
Here is your Christian one. I hated it.
Wellington, David Monster Island
Another zombie series but I've only read the first so far. Not all that good.