Wow, lots of suggestions to choose from! I just finished Wizard's Bane, and enjoyed it. I've read a couple of the Discworld books, but not most of them. I have read all of the Callahan books, and loved them, too. The Hitchhiker's "trilogy" is an all-time favorite. I haven't read the Spellsinger series, but have enjoyed the Flinx books from the same author in the past.