Here are some of the latest valid Godaddy promo codes. I just used OK9 to renew some domains and it worked awesome.

OK7 - 10% Discount on total order
OK8 - 20% off all orders of $50 or more
OK9 - 30% off .com Domain Renewals or New domain registration.

**Special Godaddy Code Valid thru 08/31/2009.
Godaddy Coupon OK25 25% off all hosting plans or any order of $91 or more.