This is a dating site for polyamorous people. Polyamory, a word taken from the Greek for "many" and Latin for "love," is ethical non-monogamy. (Go to Polyamory.org for more information, or read The Ethical Slut)
There aren't a whole heck of a lot of poly people out there, so this site is small. But if you live in a fairly liberal area of the country, it might be a big help in finding people of like mind, as opposed to swingers or folks who are cheating on a spouse.
Features include message boards, chatrooms, and the option to link your profile to your IM accounts and online journals.
I interviewed O.I., a 33-year-old hetero man looking for women, couples, and/or groups. He said, "The free account option leaves out two critical features: Search for people by distance from ZIP code, and email notification of replies. It also deletes messages after 30 days, so if you have a free account and don't check back often, you may never know that someone wrote to you. This site allows people to find other poly people for friendships or relationships, not intended to find sex partners. Very poly-aware, and generally well done."