One of my favorite online game stores, Go Gamer.com has a 48 Hour Madness Coupon sale. Enter one of the following codes before Friday Midnight (Eastern) to unlock special discounts:

• GIVEMEFIVE - Save 5% on any PC or Mac order
• GIVEMETEN - Save 10% off any PC or Mac order greater than $50

The site is also offering discounts on Chessmaster 10K ( 25% off ) and the new classic Civilization III ($5.90).

GoGamer.com has a semi-regular weekly mailing with special discounts on recently released popular games. They call it their Madness Mail, which I think is fitting - a week after Doom 3’s release GoGamer.com had it 10% off. You can sign up for the Madness Mail on GoGamer.com’s front page.