Akinator

Akinator is a popular website based on 20 Questions where an eponymous genie guesses a fictional character or a real person based on your yes/no answers to his questions. He initially asks 20 questions and then guesses a character. If he's wrong, he asks 10 more questions before guessing again, and then 10 more. If the 3rd guess is wrong, you win and you can tell him the correct answer for greater accuracy in the future, by way of a list of characters that are close to his answers, or by adding a new character through a form. Despite having been popular with GameFAQs users for a while and the character database being built by the users, CEtizens are still astounded when he correctly guesses SBAllen or the "My leg!" guy from SpongeBob SquarePants, to name a few.