http://us.akinator.com/

It's a guessing game where a cartoon genie tries to come up with the character you're thinking of through yes or no questions.

It took him a while to come up with The Vision (and he wrongly guessed Martian Manhunter first, the bastard) but he shocked me with how quickly he figured out Maria Von Trapp. I didn't even think we were close and he suddenly busted out "Is she from Austria?"