ZooGue does this every now and then. There is a limit of 2 per order, but you can place as many orders as you want. The coupon is only valid on the first 50,000 cases and will work on the both cases in the order. Shipping is $4 for one case and $6 for 2 cases. You can check out as you normally would or use PayPal.
How to use PayPal with the coupon:
Start check out normally (don't click "Pay with PayPal"),
fill out all your info correctly,
on the very last page (confining your order before you pay), there is a spot to enter a coupon code, enter "FreeZooGueAccessory" (no quotations)
then next to that select "PayPal Express Checkout"
You will be redirected to a PayPal log in page
You might need to enter your info again after logging into PayPal, like I did, but when you confirm your address again it shouldn't charge you twice. Might make a good present for any occasion.