Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
craigslist - craigslist provides local classifieds and forums for jobs, housing, for sale, services, local community, and events
Mobilizon - A free and federated tool to get our events off Facebook
classified-ads - Classified Ads is a web based free to use ad viewing and posting system that can be accessed from any part of the world to view the local ads of any area and location.
DownToMeet - DownToMeet is a platform to organize, find, and attend group events.
Geebo - Geebo is an online classified ad provider of employment, real estate, vehicles, local artists, house for sale, apartments for sale, and likewise many other types of advertisement for free.