Today is a GREAT day to hit up Old Navy! For starters, there is a $10/$50 coupon at their Facebook page (well their was - I am sure it's still there). This coupon is good in-stores only. If you have an Old Navy credit card - you get 10% off on Tuesdays.
If you prefer to shop online - they are having 30% off all new arrivals (but you can't use that $10/$50 coupon....).