I love Terry Pratchett. Currently I am reading Theif Of Time, which is a good one. Some of my favorites were Mort (the first one I read), The Last Continent, Interesting Times, Moving Pictures, and Soul Music, which was slow at first but the end was really good. I love all of the books involving Death, he (it?) is my favorite character. I can't wait to get Reaper Man, but I just can't find it anywhere...
EDIT on August 1: I just finished read Night Watch... it is now definitely my new favorite, absolutely awesome. That book would make a great movie, one I would definitely see.