The Wee Free Men by Terry Pratchett

This book introduces Tiffany Aching, a nine-year-old witch in training, who must save her inconvenient, sticky brother Wentworth when he is abducted by a fairy queen. Fortunately she has help--in the form of the Wee Free Men, tiny blue pictsies with amazing strength and little patience to help anyone who isn't a hag. This book was funny and heartwarming. I think I prefer the adult Discworld novels, but this one does have charms and an internal logic that works.