Here are the latest valid Go Daddy promo codes. I just used OK9 to renew some domains and it worked great.

OK7 - 10% Discount on total order
OK8 - 20% off all orders of $50 or more
OK9 - 30% off Domain Registration (.com)

**Special Godaddy Promo Code Expires on August 31, 2009.
Godaddy Promo Code OK25 25% Discount on all hosting plans or any order of $91 or more.