Ms. Sandwalk has discovered a new game called Blokus. I recommend it highly.
She has a description of the game on her blog and an explanation of "polyominoes"—a term used in recreational mathematics. What she didn't put on her blog is her reaction on discovering that some people think that mathematics can be recreational!!
Incidentally, she hasn't yet won a game of Blokus. This makes up for all the times when she beats me at word games.