If you've never used this, it's neat. It looks are your browsing history and tries to guess your gender. If you're history was recently cleared or only has mainstream sites it will probably guess that you're female, since most popular website (Google, Facebook, Yahoo) have more female visitors.
I was surprised by the results of one of the websites in my history:
IMDB: 1.06 (male-female ratio)
If you look at any movie on IMDb there are more male than female votes. This is even true for The Notebook, A Walk to Remember and The Devil Wears Prada. Movies that are gender-neutral like Avatar and Raiders of the Lost Ark have a 7 and 8-1 male-female ratios for votes. How could IMDb visitors be so close to balanced between men and women and the voters be so imbalanced? Where did he get the data, or did he choose the weights?
I also downloaded the "Man Proof Test" that you're supposed to be able to pass if you're a guy. I got 46 out of 52 questions right, but I think you're supposed to get them all right to pass. It was somewhat emasculating.