EDIT: It looks like they've removed this offer. I'm looking for a new Promo Code now. If you've already created a personalized card, you can save it in your shopping cart or to your account and then use the next code I find on it.
Hallmark.com is giving away a free 5×7 personalized folded card when you use the promo code
CARD4U (it even includes shipping). There aren't any upcoming birthdays that I can remember though, so I'm going to just make a generic “get well soon!” card and send it to myself. It's nice to have cards on hand for those last minute events where you need one. In fact, I have a drawer full of them, some of which include timeless messages as “Y2K is almost here!” and “I'm glad to hear you didn't get SARS.”