OMGOSH I'm all kinds of excited...
You can do this twice - per account - using the 2 different codes:
CARD4MOM and APRILCARD
1. Create an account, if you don't already have one
2. Choose and customize a card
3. Proceed to checkout, enter promo code (above)
you can even use it to make the personalized photo cards... it's awesome!
You can also choose to have Hallmark send the card for you - says they charge for a stamp - but the code clears that as well, so it's 110% free.