Any individual order that is awaiting shipment should have a simple UI for changing the shipping address. We have a lot of customers that send our product as a gift. There are a myriad of reasons why a single order might need an address change but not require a change to the customer's future orders or address book. Right now I have a customer with two pending gift orders each to a different address, and one of them needs to change, but not both. There is not an easy way for me to fix this.