Something Positive - Excellent sarcastic humor and a boneless, melting cat.
Schlock Mercenary - Futuristic mulitary humor with a main character that looks like a pile of green crap.
Penny Arcade - Really cool, put-your-money-where-your-mouth-is kind of guys who know and review many games, and the comic strip is great, too.
Ctrl+Alt+Del - You just know that they've been reading your diary to get ideas for this strip. It all sounds so familiar.
Order of the Stick - Created by game designer Rich Burlew, he pokes fun of all the D&D rules that all gamers questioned at one point or another.
Mega Tokyo - The Overlord says to look upon it an admire. And so you shall.
Sluggy Freelance - One of the oldest web comics out there and still one of the best. A blade slinging bunny and a poinging ferret. What more can you demand?
Girl Genius - A fun and adventurous story line and beautifully rendered artwork by Foglio.
VG Cats - Comic good. Snort.
Uberminion Rantings - Read Topher's many word of wisdom and other moments of clarity on his blogspot page.
Pirate Guys - Find out more about John Baur and Mark Summers, the creators of TALK LIKE A PIRATE DAY!
Steve Jackson Games - Creating games like Munchins, WarMachine, Zombies, and many more.
WizKids - The source of MechWarrior, HeroClix, and Pirates of the Spanish Main and much, much more.