Before there was online dating, Betsey Chesler met her husband through a dating service. Now he's her ex-husband. "So, I know how not to match people," Chesler likes to say. When she decided to start her own online dating service, one of the only ones that also offers video dating online, she researched the field to find what the authorities -- psychologists, marriage counselors, divorce lawyers -- had to say about personality traits and compatibility. Then she developed a series of questions. On the face of it, these questions -- about religion, education, et cetera -- seem pretty basic. They're quick and easy to answer, except maybe the one that asks you to write an essay about your favorite subject -- you. But Chesler says it's what her custom-designed software allows her to do with the answers that makes the difference. Members are told not only with which other members they match up but how close a match -- percentagewise -- each one is.