I use "Pay on arrival" to create an order number and hold that order open for a gift certificate that I will need to add a scheduled program to later on once we are contacted. This essentially makes the gift certificate a receipt for a pending $0.00 order that I can still modify. I'm currently adding a donation in order to make "Pay on arrival" available and then just deleting it later on, but those steps would be unnecessary if "Pay on arrival" was available regardless.