Wouldn't these mugs make sweet presents for children (or, let's face it, for 23-year-olds too!)?
My favourite is the Matilda one. You?
P.S. A Dahl-themed present that made me giddy with joy when I was younger was the incredible Revolting Recipes book - also illustrated by Quentin. I tried making at least half of the recipes - Mr. Twit's Beard Food, Peach Juice, Bruce Bogtrotter's Cake, Stickjaw for Talkative Parents - my mother was unimpressed.