OK Cupid - No Longer Affiliated

OkCupid.com is a totally free matching service. It's also extremely accurate, as long as (a) you're honest, and (b) you know what you want. Ok Cupid don't claim to evaluate you perfectly, but they do claim to find someone who claims to fulfill your claimed requirements, exactly. Ok Cupid firmly believe that most matching sites are just personals services; their "matching" systems are nonexistent or overly subjective.

While they have a small team, OkCupid all take math (and all that math implies) very seriously. OkCupid is a fun project for for a variety of reasons, only one of which is the actual content. They aim to be the best matching service on every front: superior technology, better math, better psychology. And of course, it's free, unlike all the others.