Old Navy is running the Stuff & Save promotion again! When you use your Old Navy, Gap, or Banana Republic card as payment, you can save 20% on any Old Navy purchase. This offer is good in-store and online.
For online orders, use the code STUFF5O when you checkout, and the discount is automatically applied to your Old Navy merchandise. For in-store purchases, I believe you have to have the Stuff & Save card. (I'm saying this based on the fact that there was a card included in the mailer for this promotion.)