1. bigcrumbs appears to offer a profitable giftcards.com rebate: a 2.4% rebate on $500 card fees are $4.95 activation + $0.44 US mail shipping, so you make 1.322%. This is important to the topic of this thread because the gift cards are Visa or MasterCard and chargesmart.com does not yet accept American Express (but their customer support says they are actively working on it).

2. I recently called chargesmart.com and was told that they now no longer authorize car payments above $1,500/month, even if you call on the phone. Also, you are not allowed to do payments on certain account numbers for some car loans from at least one car loan company that they list. I am not sure the reason, but customer service made clear it is not a software problem but a real business issue (maybe loans from certain states, intermediated by certain financial institutions, who knows).

3. williampaid started accepting American Express a couple of weeks ago. Also message #151 at http://www.flyertalk.com/forum/miles...online-11.html indicates that an updated promotion for FlyerTalkers from WilliamPaid may be forthcoming.

[Edit 12/3/2010: I hasten to hasten to add a warning that I have not completed a purchase from any of these vendors yet.]

[Edit 12/3/2010: Changed "almost 1.4%" to "1.322%" for giftcards.com. Sorry for the bad math! Also specified US mail shipping.]