The future is now:
Analogia Star Estimator
Upload a headshot of yourself and it gives you three celebrities that look like you.
The results seem pretty arbitrary--the two photos I tried gave me Holly Marie Combs (who?), Elizabeth Hurley, and Norika Fujiwara, and Linda Evangelista, Cher, and Natasha Henstridge. Clearly, the technology has a long way to go. It might help if they had a larger pool of celebrities to draw on, too--it's woefully short on people of color* and non-beautiful people (for women, at least--the men's list includes a few character-actor types).
Probably the most fun thing to do at Analogia is to click the radio button for the opposite gender, hence the subject line of this entry. The other photo gave me Scott Baio again, Takeshi Kaneshiro (LOVE!!!), and Zinedine Zidane.
* Not that people can't resemble celebrities of a different race, of course--I used to work with a Japanese Gwyneth Paltrow.