Each AMEX card registered to the SBS program is able to make a purchase at any small business, identified as a non-chain store (i.e. nearly 100% of Kosher restaurants), and receive a $25 statement credit with a purchase of at least $25.
Additionally, there are numerous non-profit organizations you can donate to and still receive your $25 credit. They likely have to be a physical location, like a school or synagogue (although that is not 100% confirmed).
Tweet me @YeahThatsKosher if you want my advice on the best AMEX cards.