For me I would say the following:
1) Dark Tower series (some are a lot stronger than others) - its really hard to say a group of so many books can hold my interest this well. (Anyone who's ever read a Fantasy series like Robert Jordan knows that it can get tiresome!! ) I mean how many books provide slang into your everyday life, well at least when talking with other friends who read the books

The following I won't give numbers - just a little bit as to what made them stand out to me:
*) The Stand - Awesome story, fantastic characters. There's a part of me that would like to survive such a plague and see what I'm truly made of.
*) Pet Semetary - This book has some scary stuff. I still get freaked out in dark buildings or being in the woods.
*) Insomnia - Fun to read. I remember not really liking the depiction Crimson King :-/
*) The Shining - If you haven't read it, do so. If you've seen the movie first, sorry. The movie is pretty good - but can't touch this book.
*) Desperation - Awesome, didn't feel the same way about the regulators.
*) Bachman Books - These are short stories ("novellas" or whatever) that King can be proud of. You can usually tell when he enjoyed what he wrote and when he didn't.
Its late and I can't remember any others for now.