Promotion Details / Codes / Coupons page @ Shutterfly.con
Shutterfly has a handy (and smart for being extra user-friendly) feature, which lets you enter any promo code (1st/2nd/3rd-party) at any time and then keeps them ALL tied to your account under My special offers and discounts. Then - as you add / remove items to / from your cart - the Shutterfly checkout system actually appears to dynamically pick combinations of the promos that have piled up in your account in such a way as to optimize your savings. (Wish other online sellers did the same!)