"Add a note" to "Print Order" output

I would like the ability to "Add a note" to a customer order AND have that note show up on the "Print Order" printout.

If a customer emails me after placing their order and wants to change order information or if I have to make extra notes about the order for some reason, I have to hand-write the changes on the printout. Please, please, PLEASE incorporate some type of ability to update order summaries AFTER the order has already been placed.