Copy Billing Address to Shipping Address

[Booostie]

We have the Billing and Shipping address fields next to each other on most of our forms (Sales Order, Quote, Invoice etc.) and often we will be inputting a custom address for both. Currently you have to manually input the address twice to get it in both fields, it would be great if there was a button that just simply copied the Billing address to the Shipping address field and vice versa!