Cool Links!

Web development

NeoCities – free static web hosting
NekoWeb – free static web hosting (I haven't tried this one myself)
Indigo's den – Links (88x31 and more!) (xaselgio.net)
Nu Html Checker – validate an HTML document
W3C CSS Validation Service – validate CSS code or an HTML/XHTML document that contains CSS
WHATWG character entity reference chart – a list of named HTML character references like &
Official Unicode Online Data – a list of all Unicode characters as a single PDF (look for CodeCharts.pdf under a version directory)
Collection of 88×31 buttons
The 88×31 Archive – more buttons
The Largest 88×31 Collection on the Internet – more buttons
A.N. Lucas's 88×31 button Collection
88×31 Collection
buttons world – a small collection of 88×31-px buttons

Programming and game hacking

Bit Twiddling Hacks – algorithms/C snippets regarding mathematical/bit operations (e.g. determine if an integer is a power of two)
The Daily WTF – software development humor
Data Crystal – technical info about games (e.g. lists of ROM/RAM addresses)
ModdingWiki – technical info about games (e.g. file formats)
Near's Respite (mirror 1, mirror 2) – game console emulators, development tools, articles about emulation (RIP Near)
NESDev Wiki – technical info about the Nintendo Entertainment System
NESDev Forum – more of the same
Programming the 65816 - Including the 6502, 65C02, and 65802 – a PDF book
ROMhacking.net – files regarding game hacking (e.g. documents, utilities and ROM patches)
The ryg blog – programming
Home Page of Evan Miller – math and programming articles (e.g. Splatoon's ranking system)
Game Boy development resources
Int10h – VileR's blog – retro PC stuff
The blog at the bottom of the sea (demofox.org) – programming
lisyarus blog – game development
Zen of Assembly Language: Volume I, Knowledge – a book by Michael Abrash

Games

Misc computer stuff

Dhole Moments (Soatok's blog) – cryptography, furries
deneb (leggi.es) – OS images etc.
moule world – links – including 88×31-pixel buttons
Wiby – a search engine for the classic web
Lira's home page – Famicom keyboard etc.
Absorptions (windytan.com) – O. Räisänen's blog; signal processing
Byte Cellar – retrocomputers
eevee's Fuzzy Notepad – game development, furries, etc.
Hackaday – hardware hacks every day
homepage of Gravis – old computers
Hugo Landau – computer articles
Joel Yliluoma (Bisqwit)'s home page
Ken Shirriff's blog (righto.com) – CPU die shots etc.
Reenigne blog – “8086 microcode disassembled” etc.
Nicole Express – a retro gaming hardware blog
ToughDev – vintage computing – retro PC articles
Software Folklore – interesting computer bugs
The Cursed Computer Iceberg Meme – interesting computer bugs
The Future Is Now – Misty's blog
ePanorama – hobbyist electronics
Vintage Computing and Gaming – Benj Edwards' blog
Vogons – a retro PC forum
MCbx Old Computer Collection (oldcomputer.info) – old computer stuff
GUIdebook – screenshots of operating systems
Ethically sourced Lena picture – a replacement for the well-known Lena/Lenna test image
ubitux/blog – programming, math
Lospec palette list – colour palettes for pixel art
programming pages (sirrida.de) – bit permutations etc.
Datagubbe – essays on computers, etc.
oldskool.org – retro PC stuff
thefox – NES development
Retro Game Mechanics Explained – articles (website of the Youtube channel)
chjara's links (archived)
Tom Forsyth's Tech Blog – some advanced stuff
Vogons – a retro gaming forum
David Buchanan's blog – advanced computer stuff (“SIMD in pure Python” etc.)
Just a QR Code – a QR code generator with no ads
BitSavers – old drivers, manuals, datasheets and computer magazines
Susam Pal's blog – on technology, math, etc.
Susam's Wander Console – browse random websites in the Wander network
Wikimedia Downloads – offline copies of Wikipedia in XML format
Booting Linux on Intel 4004
GUIdebook – screenshots of graphical user interfaces
OldVersion – old versions of programs
CPU Collection – photos of CPUs
Scary Beast Security – Chris Evans' blog
jsgroth’s blog – emulator development
oldskooler ramblings – Trixter's blog
DiscMaster – search old files from Internet Archive
The 7 segment decoder, done wrong – uses modified BCD

Webcomics

Savestate – retro games and furries
Freefall – science fiction adventures of an alien and a wolf
General Protection Fault – working with computers (I haven't read very far yet)
StupidFox – a feral fox and his friends
VG Cats – cat characters playing video games
Runaway to the Stars – life in space

Browser games

Hello Wordl – a Wordle-like game with adjustable word length
FoxiMax – a somewhat Wordle-like game
Semantle – a word-guessing game based on semantics
Cemantle – another word-guessing game based on semantics
Pedantle – guess the Wikipedia article by guessing words in it
Train Planner – build train tracks between stations
Wplace – draw pixel art on the map of the world (multiplayer)
Morsle – practise listening to Morse
Susam – Guess My RGB – try to estimate the amount of red, green and blue in the colour shown