If you have a Diners Club card, don't forget that InsideFlyer also has a 3500 Diners point promo that is valid through 8/31. Of course, this is worth only 1750 miles with most airlines, but 3500 BA miles during the summer double miles promotion. Be sure to allow enough time for the IF points to post prior to the BA 2-1 transfer deadline on 8/31.

http://www.insideflyer.com/diners