I tried to use Shelfari (social network for bookworms) to catalog all the books I have ever read, but I hit around 400 books and that was such a tiny fraction of the total that I gave up, it was just too huge of a task. I can only estimate but I guess I've read somewhere between 6,000 and 10,000 books in my life.
When I was a teenager, I was truly voracious. One night I read two books then started reading Zelazny's original Chronicles of Amber series, and ended up staying up all night finishing all five of them too. So, seven books in one night. That's my record and I doubt I will ever surpass that. (Granted, the Amber books are not exactly huge.)
My favorite genre is hard science fiction (Niven, Pournelle, Bear, Bova, and the like). My second favorite is horror. I've probably read thousands of books just from those two genres.
About ten years ago, I was jonesing for some books, and I dug around in a closet upstairs, and found like 200 romance novel paperbacks, apparently left behind by the previous owner of this house. I ended up reading all of them too, just because I was desperate. (Romance books are *extremely* formulaic, makes them kind of funny.)
Right now, the current stack of books I am working through includes:
'Event' by David Golemon
'Marker' by Robin Cook
'Red Lightning' by John Varley (he's great)
'Dark Tower VII' by Stephen King
'The Collected Short Fiction of CJ Cherryh' by (duh) CJ Cherryh
'The Runes of The Earth' by Stephen Donaldson
...and a pile of others whose titles I can't quite read from here.
I tend to buy books by the stack, around 20 at a time, preferably hardback. Barnes & Noble has a 'bargain bin' with some good deals. Unfortunately, i've really picked it over, not much left that interests me, and the library ran out of books that I haven't read that I want to read, so now it's back to full price paperbacks for me for the next stack.