This little doohickey is a pocket brain. The 20Q contains a neural net that plays 20 questions with the user and is apparently scary smart. I played 20Q against the web version, and it correctly guessed the thing I was thinking (a Pikachu Pokemon) in about 22 questions. Amazing.

The toy version is available for $10-14 (although the Amazon appears to be out.)

I learned about 20Q on Cool Tools. Great site. (Here's their article on the matter. It has a lot more detail than mine.)