When I bought a Nook Color for my wife’s birthday, I also bought the obligatory gift card to get her started on the road to eBooks. It is actually easy to use a Barnes & Noble gift card to buy eBooks for the Nook, unfortunately B&N’s web site has the procedure fairly well hidden. But not from the eyes of Google! Here is the link.
How to Redeem Gift Cards for NOOKbooks
It’s pretty straight forward. Just go into your account settings and click on the Manage Gift Cards for NOOKbooks link. Once you save your gift cards there, your eBook purchases will be paid with your gift card balance before charging your credit card.