I got sent a great book, Visual Aid: Stuff You've Forgotten, Things You Never Thought You Knew and Lessons You Didn't Quite Get Around to Learning by Draught Associates (Black Dog). It's full of lovely diagrams and informatics on all kinds of subjects, exactly as the title says. Flicking through it I learnt some useful things about hats, poker hands, planets and the relative size of fictional spaceships. It's broad enough for kids but smart enough for adults. Useful as a last-minute present for the design-conscious or the hard to please.