If you are looking to register/renew a domain name it is advisable to check checking Internetuals as GoDaddy coupon codes shall be added frequently to help you save money on your domain purchases.

goxtgi200c - $7.05 .com registrations and renewals

gdp0804a or gdp0804b or gdp0804ad - 30% off .com registrations, transfers or renewals - $7.19 .com domains (Expires: August 31st 2008)

downforce - 15% off registrations (works with .net and .cc not sure about other extensions)