Not all dating sites are well suited to people in open relationships. Most mainstream dating sites are geared towards singles, or people in committed relationships looking to cheat. Those in an open relationships who are looking for casual, physical relationships, or for potentially serious new partners, there are some good options for Torontonians. This list will be updated over time, and you can also send us your recommendations.
OkCupid takes a relatively unique approach to matching potential partners: there are hundreds upon hundreds of questions for you to answer, on a variety of topics (sexual and not). A magical algorithm uses the answers to give you a match percentage with every other person on the site. Surprisingly, the match percentages tend to be a pretty good indication of potential compatibility.
OkCupid has a significant number of users who are either in open relationships, or open to connecting with someone who is. You can't search specifically for such users, but if you answer enough questions, and are willing to spend the timing sifting through enough users, you'll find them. In general, people on OkCupid are interested in forming relationships that are not only casual physical ones. Oh, and it's free!
Cafe Desire is a highly regarded dating site for swingers, where members report a high success rate in terms of meeting other people and couples who are potentially good matches. There is a very inexpensive lifetime membership fee which is well worth the value, especially relative to the cost of some other similar sites.
Yes, the same place you may go to find a lawnmower is also a good place to find potential partners. Look under "Casual Encounters", and you will find all various permutations and combinations of men, women and transsexuals looking for combinations of the same. Just like any use of Craigslist, but even more so, you need to be careful about sharing person information or pictures with just anyone. Significant filtering and screening is required to find good potential matches. And yes, Craiglist is free.
Menage a Quatre is associated with the nightclub of the same name (also referred to as M4), and has a social networking type of setup. There are many couples on the site, as well as singles, all looking to connect with others, mostly for more casual encounters. The site offers a convenient way to share pictures only with specific others, by allowing you to password protect any of your pictures that you choose. The site has free and paid subscriptions, but the free type should suffice for most.