Gaming

The one I use most is:

https://www.dlcompare.com/

I avoid the key sharing sites like Eneba, Kinguin, Gamivo, HRK, G2Play, G2A, DIFMARK. These are like eBay but for game keys - I avoid them as you don't know where the keys have come from in the first place. I have used Instant Gaming, CDKeys and MMOGA without any problems (anything with an "Official Store" flag is fine).

The other one I like is:

https://isthereanydeal.com/

This scans all official stores and you can set up alerts for when games drop in price.

PCGamingWiki aims to list fixes and workarounds for every single PC game - https://www.pcgamingwiki.com/

Widescreen monitor support site - https://www.wsgf.org/mgl

A list of useful PC programs - http://pcprograms.surge.sh/

And this one on Reddit with descriptions of the programs (overlaps with the one above) -

https://www.reddit.com/r/pcgaming/comments/batgd9/a_gamers_guide_to_windows_programs_2019_edition/

(and https://www.reddit.com/r/pcgaming/comments/9bbjk9/1_year_ago_i_created_an_adfree_website_that_lists/)

Steam (obviously).

Origin - Electronic Arts (EA).

Uplay - Ubisoft

Epic Games (Free games every Thursday)

GOG - Good Old Games

Twitch Gaming (Free games with Amazon Prime)

Itch.io (Good but lower priority)

Optifine, I can't live without it - https://optifine.net/downloads

My favourite shaders that I use with Optifine are Sildur's Enhanced Default - https://sildurs-shaders.github.io/downloads/

And then there's Chunkbase - https://www.chunkbase.com/

Shape generators:

Lots of different shapes - https://www.plotz.co.uk/

3D shapes - http://oranj.io/blog/VoxelSphereGenerator

Circle generator - https://donatstudios.com/PixelCircleGenerator

Shapes from an equation - https://www.desmos.com/calculator/w9fetmljyf