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

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

Raddle - A web-based forum where users submit links, pictures, posts, etc.

TBPChan - TBPChan is a self-hosted website that promotes free speech on an anonymous message board similar to...

Exhentai - Exhentai is an anime/manga image site which has a lot of hentai images (as the name implies) and content (such as doujin/doujinshi scans from Japanese magazines, CG artwork, hentai manga series, fan art, etc...)

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