DOSbox - Extremely powerful and versatile DOS emulator.
FileZilla - The only FTP client you will ever need.
JoyToKey - Keyboard emulation for joypads. Very useful.
Mozilla - Damn fine web browsers, mail clients, and page editing software, among others.
Opera - The best browser in the universe.
Acts of Gord - Keeping the retail faith.
Angry Video Game Nerd - Hilarious reviews of the worst video games ever made.
Ashens - Reviewing cheap crap for comedic purposes.
Axe Cop - The best webcomic ever. EVER.
Cinematic Titanic - The modern revival of Mystery Science Theater 3000 - riffing on old, obscure movies.
I-Mockery - Pop culture mockery at its best.
IT-HE Software - Damn funny game "anti-walkthroughs" that have to be seen to be believed.
Nostalgia Critic - Awesome movie reviews.
RiffTrax - The other half of the MST3K crew makes fun of modern movies.
The Spoony Experiment - Hilarious game and movie reviews.
Two Best Friends Play - Absolutely hilarious game commentaries.
Anime Abandon - Reviews of the absolute worst (and best) of 90s anime.
The Cutting Room Floor - See all the strange stuff that was cut from your favorite games.
Double Jump Books - The best strategy guide writers in the world.
Hardcore Gaming 101 - Articles about games, ranging from the great to the obscure to the completely terrible.
Let's Play Archive - The best of the numerous Let's Play threads on Something Awful, all preserved here.
Lost Levels - Information on beta and unreleased games.
The Mega Man Home Page - Still the best Mega Man resource on the Internet, bar none.
Scorched Earth - The greatest tank combat game of all time.
Sega-16 - All things Sega and 16-bit.
Speed Demos Archive - Guys with mad skills breezing through games in record times.
Until We Win - Playing the most infuriatingly difficult games of all time... until we win.
Unseen 64 - More beta and unreleased game stuff.
X-CulT - Yet more beta and unreleased game stuff.
Good Old Games - The best PC games of all time, available DRM-free and dirt cheap to boot.