Discover Card offers a Double Cash Back bonus for your birth month. So, if you were born in Feb or March you can sign up now. This is in addition to the other cash back you already get with them.
Rules from this site:
Sign up to earn 2% Cashback Bonus on up to $500 in purchases from the first day of the birthday promotion month for which you enroll (or the date on which you sign up, whichever is later) through the last day of that month. Purchases earning 2% Cashback Bonus will not count toward your total annual purchases to determine your tier level. These purchases must post to your account by the last day of the month. Allow up to 5 weeks for this reward to be added to your Cashback Bonus account. See Cashback Bonus Program Terms and Conditions for further details about your reward program.