Okay, I just found this. Old Navy has "easter egg" coupons on their site.
Check this out. Click on the Blonde gal in the lower right corner for a coupon for $50 a purchase of $100 or more (and you can combine it with another coupon). These are changing fast, so post what you find!
PS. looks like this one is gone, but the airplane flying by in the pick with the dark haired mannequin gives you 20% off.
Hurry! These are running out fast and will change every week! Fun!