Some questions used to determine whether someone may have prosopagnosia:
Would you have problems finding your party's table in a restaurant?
Would you recognize a famous actor or politician, if you saw him or her unexpectedly in the street or in a restaurant?
If somebody looked into your office, asked a questions and left, would you be able to recognize him or her some minutes later in a group of people?
At larger functions or parties, do you talk to someone for a couple of minutes and then find you can't remember his or her face a few minutes later?
Picture yourself in mall or at the airport: If someone you don't recognize greets you and starts talking to you in a very familiar way, what do you do? (Typical answer from someone who has trouble recognizing faces: I would try to find out from his or her voice and from the subjects discussed, who he or she might be.)
SOURCE: Thomas Grüter
To take a longer test, using celebrity faces, go to: www.icn.ucl.ac.uk/facetests/ and click on "test my face recognition"
For a layman's website about prosopagnosia, go to home.earthlink.net/~blankface/prosopagnosia.shtml.