Those with a Discover More($100 bonus) or Discover Miles, you can now earn 2% cash back bonus for all online purchases from Nov. 15th to Dec 31st of this year. The cap for cash back is $1000 in purchases and you can log into your account to sign up.
From the website:
Sign up to earn 2% Cashback Bonus on Internet purchases from 11/15/10 (or the date on which you sign up, whichever is later) through 12/31/10, subject to a cap of $1,000 in purchases. These purchases must post to your account by 12/31/10. If a purchase is not classified as an Internet purchase, it will not qualify. Purchases earning 2% Cashback Bonus will not count toward your total annual purchases to determine your tier level. Allow up to 5 weeks for this reward to be added to your Cashback Bonus account. Only Discover More, Open Road and Motiva Cardmembers are eligible to participate in this program. See Cashback Bonus Program Terms and Conditions for further details.