I met my bf on okcupid.com
I'm a math geek and I liked our statistical probability of compatibility based on our values and lifestyles after answering the 3000+ questions on there. Plus the questions are a fun timewaster!
Seriously though, after living with him for 2 years, its really really accurate the areas in which we dovetail and the 13% we disagree on!
Then again, he and I were both open to dating people from all over the world... if I had limited myself to men in the dating pool where I used to live I would have had to settle for the types of guys who have profile pics with either a fish, a dead animal, a motorcycle, a boat, or another woman with her head cut out of the picture with a scissors.