Lots of classic stuff - cyberpunk magazines like Mondo2k and the original Boing Boing, books, music, CD-ROM disk inserts.
WELCOME TO CYBERSPACE, VIDEO KIDS. YOU'VE FOUND ⒶNNARCHIVE, a permanent(?) collection of game media, archeaology, and artifacts for you to peruse.
A wiki dedicated to the Commodore-64 home computer.
The archive of 80's and 90's computer magazines of all sorts and kinds, brought to you by archive.org. Including some you've probably never heard of but might want to peruse out of curiosity or a sense of nostalgia.
A public archive of Atari history, including games, documentation, and user magazines from days gone by.
This website has a good archive of abandonware and some interesting web apps, like an online disk editor and visualizer for .d64 disk images.
The Atari software and magazine collection at the Internet Archive.