for reference, the 10% off codes at WMK are generally referral codes and never expire. So use it or one of the others every time you're on the site. They also work on Everything AFAIK, including on DotD, blowouts, open box, closeouts, etc. Higher percentage codes are limited time but I don't think I've seen 10% ones expire unless one was an additional 10%.
Great site, I have ordered more from WMK in the last year than anywhere else I think.