Well, now I know how I'm filling out a Discworld collection. I might have to actually start reading it:
Humble Bundle has 38 Discworld books for $18.
I'm really interested in whether this is a complete set of Pratchett's discworld books. I must confess I'm not too interested in another argument about what order to read them in. :P
Edit: A quick wiki answered my question. This contains all of the novels except the Last Hero (presumably because it's illustrated?) and the last two (Raising Steam & The Shepherd's Crown)