Social groups and mailing lists that include social event planning are listed here by geographic location. Many regional polyamory groups are listed on Yahoo Groups -- try this search on polyamory. (See below.) Meet helps people meet other people who share their interests.
Each interest group meets on a specific day of the month at locations that the group members vote on.
Currently housed in a 4400 square foot main building (with several annexes) near downtown Seattle, this organization is unique in that it strives to serve the local communities which comprise its region's sex-positive culture (e.g., the BDSM community as well as elements of the swing community, and everything around and in-between).
This organization is a good starting point because it offers a wide variety of events, classes, dances, vendor fairs, informal social evenings, guest speakers, an extensive library, and discussion/support groups, with something almost every night of the week, and because gender and orientation are not barriers to membership (for example: single men are as welcome as single women).
Offers support and discussion meeting, e-mail discussion lists on yahoo, and other events.