I think this has been around for a while, but this is the first time I've heard of Akinator. It's a 20 questions program that doesn't follow the standard yes/no tree structure. It uses some kind of probability system, which allows it to have more than 1,048,576 people to choose from. You can have it guess real people (I tricked it with Rick James [bitch!]), but I've had more fun making it guess video game characters. So far it's been almost spot on. I've had it guess Alucard, Cortana, Terra, and it almost got Marcus Fenix (it chose Dominic Santiago instead).

What video game characters can you stump it with?