OkCupid is a free site with an interesting mix of dating and community site, due at least in part to being created by a handful of Harvard hackers (C++ and Lisp are included in the list of otherwise spoken languages). It’s non-dating claim to fame are user-created tests, ranging from a Myers-Brigg like dating type to measurements of many obscure preferences.
The dating part of the site is well-developed with plenty of space to talk about yourself and a good photo system with cropping and captions. Matching is done using their own algorithm, which looks for compatibilities between answers to user-submitted questions. For each one, you give your answer, as well as the answers you’d want to see in potential mates. These are also used as relative measures such as telling you that you’re more political than a match, or that a match is more emotional than her peers.
The population on the site is less mainstream than others: more off-center politically, more bisexuals, and wider range of drug habits. It makes for some interesting browsing, though as with noted in my Plenty of Fish Review, you can’t hide profiles you’ve already seen.
Though a free site, OkCupid offers a number of innovative features not found elsewhere, including user-driven tests and personality matching. These features and an electic community make it interesting even for those not dating.