On My abandonware you can download all the old video games from 1978 to 2010 for free! You can play Pacman, Arkanoid, Tetris, Galaxian, Alter Ego, or Blackthorne, Civilization, Sim City, Prince of Persia, Xenon 2, King's quest, Ultima, Kyrandia, The Incredible Machine, Another World, Test Drive, Flashback, Lemmings!
And more, of course.
A 100% compatible replica of the famed SB 1.0 sound card. 8-bit ISA card. Full bill of parts. Even has a hex dump which turns an Atmel 89S51 into an 80C51 DSP chip (if you don't feel like buying one from China).
CC-BY-SA v4.0.
Free downloads of older shareware and abandonware games, applications, and utilities.
An application which downloads and archives Windows Updates for offline installation or slipstreaming.
A website that lets you search out and download missing .dll files to fix a botched reinstall or application upgrade.
The website for a classic space trading/warfare game called Elite run by one of the original authors. Includes a lot of information and even the novella which was published with the original version.
A technical reference site that has lots of odd information, most of it PC related. Data formats, file extensions, datastructures and algorithms of sundry kinds and uses, hardware specs, microcontrollers, history, advice... there's a lot of stuff buried in here. If you need something you could do worse than check here first.