My school's library recently bought the entire set of Horrible Histories, Horrible Science and The Knowledge
I do have quite a sizeable collection at home, though.
Anyway, Discworlds are always good, I'm reading James Clavell's Shogun now (nearing the end), it's damn good, I've also read King Rat by him and I planning on either Tai-Pan or Thud! (new Discworld book) next.