Here are some links that are affiliated with me:
Twitter
Steam
YouTube
Duke4 Forums (note that you will be needing an account to access my profile)
Doomworld
Backloggd
VGM Playlist

Some links that I found useful/worth looking at:

WinWorldPC: This site has a lot of downloads of abandonware stuff like
pre-NT Windows that you could find in there easily and other obscure software in there.
Internet Archive: This site is self-explanatory as it has been used by
countless people on getting software here and is also being sadly
summoned in court for piracy.
MyAbandonware: Abandonware games in here that are not supported by
the game devs anymore.
Ken Silverman's website: The guy who made the BUILD Engine has a
website that I would recommend looking into it if you are a BUILD Engine
fan because it has the source code, a download of Ken's Labyrinth and some other stuff like BUILD2.
ToastyTech: A website that I stumbled across couple of years ago.
I like the aesthetic of the website. You should definitely check out "The Graphical User Interface Gallery" that has some satirical takes
on OSes.
The Cutting Room Floor: Beta/Alpha content of video games always
interested me, and if you're interested in that content,
why not check this site out?