Just finished reading The Wee Free Men, a book set in the Discworld universe, after completeing Going Postal. Now I just need to read through A Hat Full of Sky, and I'll be almost all caught up on my Discworld, minus Thud!.
Quick mini-review. It's classic Discworld, although slightly blunter since it's meant for "young adults" although I'd think a "young adult" would be more than capable of reading straight Discworld. But that doesn't mean it's any less entertaining.
If it were going to be in any of the other storylines, it would be a "three witches" story, although it concentrates on Tiffany Aching, a young girl just discovering what it means to be a witch. She discovers the Nac Mac Feegle, who assist her in fighting the invasion of fairy monsters from another world.