American Airlines gift cards
Another data point:
I got my platinum card last weekend and enrolled American as my 200 airline-credit airline of choice. I charged four separate $50 gift certificates on Monday. The $50 charges each posted yesterday. The charges showed up as "Misc. Charge Order/Prepaid Auth." or something similar. My account was automatically credited four separate $50 credits today. I did not call, SM, etc; it just happened.