Meetup.com is a good place to find people interested. I looked last night for a meetup here, and although there isn't one organized through meetup, there is a list of about 60 people interested in one.
When speaking of various forms of non-monogamy...it ain't poly if you're just fucking around.
While polyamory, open relationships, and swinging are all distinctly different approaches to non-monogamy, they are not mutually exlusive. Folks can, and some do, engage in more than one of them at a time--and it's all good.