Through Sept. 30, 2009 members of the dining programs of Alaska Mileage Plan, American AAdvantage, Delta SkyMiles, Northwest WorldPerks, United Mileage Plus and US Airways Dividend Miles can earn double miles for qualifying dines on Monday, Tuesday and Wednesday. You must register for the promotion with your preferred frequent flyer program and be an Online or VIP member.

Bottom line: Invite a friend for lunch, pay his portion of the bill with your credit card tied into your dining program and have him pay you cash for his portion of the bill (that is, if he isn’t going to fight for the same privilege to get the miles).