Facial recognition software company Face.com started out by making it easier to tag friends in Facebook photos, but the company's API has grown more capable over time, and the latest release includes automatic age detection.
Face.com's age detector analyzes facial features to come up with three numbers -- a minimum age, a maximum age, and a best guess -- as well as a degree of confidence for each.
The software's age estimates seem to be quite accurate, based on celebrity example pics floating around the test website for the new feature.
It does seem to be flummoxed by a picture of the Eleventh Doctor, though. It estimates he's in his late twenties, when everyone knows he's over 900 years old. (Actor Matt Smith is 29, though, so Face's guess of 27 isn't too shabby at all.)