Links
It might be worth saying that I don't endorse any of these links.
Personal Websites
https://ninipro.neocities.org 🪨🪨🪨
https://linuxreviews.org/LinuxReviews
https://world-playground-deceit.net/
https://blogchan.pages.dev/ (A personal blog running on imageboard software.)
https://thuleanotherworld.com/
https://xahlee.info (A lot of Emacs-related stuff)
Wikis
Otaku-related
https://vndb.org/ (kind of a Wiki)
https://ostan-collections.net/wiki/index.php/Main_Page
https://en.touhouwiki.net/wiki/Touhou_Wiki
Computer-related
https://wiki.gentoo.org/wiki/Main_Page
https://wiki.osdev.org/Expanded_Main_Page
https://www.nesdev.org/wiki/Nesdev_Wiki
https://igwiki.lyci.de/wiki/Main_Page (beware, this is the second iteration of the Install Gentoo Wiki. The original one died a slow death and is plagued by spammers.)
https://texteditors.org/cgi-bin/wiki.pl
https://www.chessprogramming.org/Main_Page
https://rosettacode.org (This one is especially great if you're learning some obscure programming language (e.g. Forth) and don't know how to do basic algorithms or whatever.)
http://www.sizecoding.org/wiki/Main_Page
https://sinclair.wiki.zxnet.co.uk/wiki/Main_Page
https://emulation.gametechwiki.com/
Others
https://www.sigidwiki.com/wiki/Signal_Identification_Guide
https://wiki.bibanon.org/Main_Page
https://nethackwiki.com/wiki/Main_Page
https://psychonautwiki.org/wiki/Main_Page
https://libregamewiki.org/Main_Page
https://www.explainxkcd.com/wiki/index.php/Main_Page
Places to chat (imageboards, textboards, forums, BBS)
https://www.bienvenidoainternet.org/ (I don't speak Spanish, don't nail me on this one if you speak Spanish and dislike it. It's just here because I find it cool.)
ssh://bit:byte@whisper.onthewifi.com (currently broken)
Learning
https://developer.mozilla.org/en-US/docs/Learn_web_development
https://eloquentjavascript.net/
https://learnabout-electronics.org/
Hosting
No Know-Your-Customer
Know your Customer
https://www.nearlyfreespeech.net/ (They're great, if you don't mind the KYC issues and don't require more than just web hosting)
Resources
Books
Art
Privacy, Security, and Anonymity
https://geti2p.net/en/, https://i2pd.website/, https://i2pplus.github.io/
https://github.com/netblue30/firejail
https://github.com/markqvist/nomadnet
https://spyware.neocities.org/
Operating Systems
Hobby OSes
https://github.com/klange/toaruos
https://duskos.org/, https://collapseos.org/
Services
Pastebins
https://defuse.ca/pastebin.htm
File hosts
Cryptocurrencies
https://bitcoinvn.io (I haven't tested this one, I don't know whether it's a legit service or not. Do your own research.)
Archives
Otaku
https://learnjapanese.moe/ (Includes a guide how to play visual novels on Linux and FreeBSD.)