Originally Posted by
TheDudeAbides
Double Miles for AA on Mon, Tues, Weds has been extended until 9/30. No registration required.
"Great news. You now have until September 30th to dine on Mondays, Tuesdays and Wednesdays for a double helping of American Airlines AAdvantageŽ miles*. For Online Members, 3 miles per dollar becomes 6! For VIP Members, 5 becomes 10! All this with no registration required."
Also UA (same no-registration way as AA). Please see the sticky "bonuses" thread for more, it already mentions more ailines.