I wanted to relay a hair-raising statistic found in a Scientific American article by Robert Epstein:

In 2005, using eHarmony's own published statistics, a team of credible authorities--among them Philip Zimbardo, a former president of the American Psychological Association--concluded in an online white paper: "When eHarmony recommends someone as a compatible match, there is a 1 in 500 chance that you'll marry this person.... Given that eHarmony delivers about 1.5 matches a month, if you went on a date with all of them, it would take 346 dates and 19 years to reach [a] 50% chance of getting married." The team also made the sweeping observation that "there is no evidence that ... scientific psychology is able to pair individuals who will enjoy happy, lasting marriages."

http://www.sciam.com/article.cfm?id=the-truth-about-online-da&print=true