Membership Rewards-earning personal American Express cards can earn double miles on gas and groceries for the next year (through March 15, 2010 anyway).

Registration is required, which is brilliant, only give the miles to those who are striving for them.

And they cap the bonus at 1,000 miles per month. Used to be similar sorts of offers might cap bonuses at 10,000 total. Here they spread the bonus out over a year, whch means you need to consistently use the card over time in order to max out. Habit-forming.

To me, annoying, I love promos I can get excited about in a single shot and go crazy with. This is just a good offer for gas and grocery spend over time, and I suppose some folks will exceed the cap or continue their spending habits using this card past March 15, 2010.

But if it you have a Membership Rewards Amex you should register, of course.