The Light Fantastic
Found this second book in the series more enjoyable than the first, maybe because I finally got the hang of all the strange physics and specialised terminology of the discworld.
Terry Pratchett's humour is very visual -- a lot of elbows in stomachs and quick dialogue. Someone should make his work into a movie. I have a hunch that it may work as a movie.
In other news, Pratchett voices his annoyance about an article in Time that said that Rowling didn't even know she was writing fantasy. Here is Pratchett's definition of fantasy in a speech given at the Carnegie Awards.