Abandonia

Abandonia.com is heaven for old school gamers.
It offers information about tons of abandonware but mainly old games (abandonware is software which is no longer being sold or supported by its copyright holder).
You can see the year that games were released, screen shots of different levels, and the best part (get this): you can download the old games!

I went over some of the categories and ran across LOTS of games that I spent hours playing.
The list of familiar games (games that I played for at least several hours each) was so long that looking back makes me feel like I spent too much time on the PC (and I can remember at least 10 more games that I used to play but didn't find there).

Check out this list of games that I used to play back in the day (and I found there):
Aladdin Alley Cat Altered Beast Arkanoid Blues Brothers Bubble Bobble Bumpys Arcade Fantasy Cd Man Dangerous Dave Golden Axe Mortal Kombat Operation Wolf Paperboy Prehistorik 1 Prehistorik 2 The Simpsons - Bart vs the Space Mutants Ugh Zool A Nightmare On Elm Street Airborne Ranger Castle Wolfenstein Double Dragon Flashback Ghostbusters 2 Prince Of Persia Prince of Persia 2 Wings of Fury Wolfenstein 3d Lemmings Simcity Classic Michael Jordan in Flight California Games II Budokan The Incredible Machine Ski or Die Summer Challenge Skate Or Die Bouncing Babies Rampage