I’m sure you have heard that Six Sigma is no longer exclusive to manufacturing processes or to the shop floor. It has evolved and has been used to improve processes in the service industry as well.
In fact, you can use Six Sigma principles to marketing and sales. Here is a presentation featured in Six Sigma Zone about how to use Six Sigma principles to marketing.
Six Sigma : Your Resource for Strategic Management. Meikah Delid. Eversun Software 2006.