This article was written for the participants of the Discord server owned by Yakui. If you're interested, join us.
Please be aware that several of the sites mentioned include groups that are racist.
Game
lainTSX is a translation of the PS version of Lain into English by an overseas volunteer, and made to run in a web browser.
Fun
A cyberpunk magazine created by lainchan members.
They are currently working on a music-themed lainzine.
Community
A community that split off from the TSUKI Project.
Boards
R.I.P. Arisuchan
Personal
OS
irc
ircs://irc.rizon.net:6697/wirechan
ircs://welovela.in
telegram
pleroma
These are all the SEL communities that I know of. If there are others, please let me know via DiscordServer.
PS: Thanks for letting me know! I've added the sites.