Mobilizon - A free and federated tool to get our events off Facebook

4chan - 4chan is a simple image-based bulletin board where anyone can post comments and share images.

Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.

Lainchan - Lainchan is a great imageboard package, actively building on it and adding a lot of features and...

DownToMeet - DownToMeet is a platform to organize, find, and attend group events.

7chan - a simple image board alternative to 4chan small but still a nice community with much more rules...