Mrs. G2244 got this one in an email:

Dear Mrs. G2244,

Now you can earn DOUBLE MILES when you use your card for all of your everyday purchases. Spend at least $2,500 on your Continental Airlines World MasterCard®, through February 28, 2010, and you'll earn double miles on all additional purchases you make.1

And that's not all!

Earn BONUS MILES on top of your DOUBLE MILES.
If you spend $3,000 you'll receive 1,000 BONUS MILES–on top of the double miles you've already earned.2

Earn even more BONUS MILES.
If you spend a total of $9,000, during the same time period, you'll earn an additional 1,500 BONUS MILES. The more you use your card, the more you'll earn.2

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Interesting in that I got a different one where they reward me for more use (as opposed to greater spend). That one is covered here:
http://www.flyertalk.com/forum/continental-onepass/1012275-co-world-mastercard-promo-smart-smarter.html