Freakonomics linked to a series of puzzlers from a Harvard research project. Being an impatient sort, I opted for the shortest-- a face recognition test. Simply put, they display a face (face only and a bit "off" from a normal portrait of the subject), you type the name (or say you don't know), they display the correct answer and you say whether you're familiar with the person.
Anyway, I did very poorly, only recognizing 25 percent of the people with whom I was familiar (I got Obama and George Clooney and Scarlett Johannsen :-). I've always been poor at facial recognition (and sometimes, more now, at remembering the name which goes with the face I recognize) which has often made me awkward in social events. Or, possibly it's because I've had below average exposure to social events that I never developed the neurons needed to recognizing and distinguishing faces. That's what some of the latest brain research might indicate, if you believe Malcolm Gladwell.