Home for the holidays I found my copy of the Klutz book of Knots. I spent an hour on the floor having fun, took the book home, and have been referencing it all year for everything from shoelaces to extension cords.
Some are more eternal than others (Icky Poo) but as a child I never had one that I didn't completely devour. Any time I need a gift for a friend's young child, Klutz immediately comes to mind.