In reality, just about any gift card will do for time-shifting purchases into the promo window, but store gift cards can be rather limiting. Gift cards backed by a major credit card issuer are an attractive option since they can be used just about anywhere. Unfortunately, such cards usually come with activation (and possibly other) fees.
But guess what? AmEx gift cards have no inactivity fees, no expiration dates, no fees for the recipient, and there are currently promo codes floating around out there for waiving the activation and/or shipping fees. You can buy a consumer card in amounts ranging from $25-$3k. Moreover, if they’re lost or stolen, the remaining balance can be recovered.
Through 08/15/12, you can use code EMDADWEL to waive the $3.95 purchase fee. Similarly, through 06/30/12 you can use codes EMMOTWEL or REMMOTWEL to get free 2nd day shipping (an $8.95 value). Or you can use codes GRADUATE or FATHER617 (likewise good through 06/30/12) for free standard shipping (a $5.95 value).
If you use online rebate services eBates, FatWallet, or BigCrumbs then you can get additional cash back by going through their links. Pretty slick, and a handy way to break through reward tiers now that you can no longer buy dollar coins from the Mint with a credit card.