I know I have seen this before a long time ago but wanted to update. I just ordered some items on Amazon that have the free shipping above $35. My total order was well over that amount but their system still added the shipping cost to my order when I would go to place the order. I called Amazon customer service and explained the situation. The agent stayed on the phone with me while I placed the order, then immediately grabbed it and took the shipping cost off. I'm pretty sure this will only work with things being shipped from the Amazon warehouse via USPS. I used my PO Box here for the shipping address.
Amazon, free shipping
Not a long time ago - July this year when I posted the same information:
barnes and noble has always had free shipping on orders over 25. they do not sell all the products that amazon does but if it is books games etc, just an fyi
If that's the case, Amazon owes me roughly $Texas in shipping charges I've paid over the years.