I know it is still not possible (yet) but I remember some minor debate about justification for such a feature.

We have recently taken on several Government agencies that MUST use a PO to place their orders.

How it works- We get order, we verify the order and verify the PO which is faxed or emailed via pdf. (sometimes they send it before we ask) We fill order and get paid.

Currently it's a pain.
We have to hope they read the site and contact us rather than surf away.
We have to take the order over the phone.
They generally point out they already have their shopping cart full of what they want.
We explain "we are a bunch of po-dunk morons that don't know how to actually operate an online store and they must repeat the order verbally..." well that's what I feel like they hear.

Even for our established accounts it's not always the same person ordering. They look through the approved vendors list, there we are, they hit the website and the fun begins anew.

What we would like...
"Government Orders Click Here"
A form appears with all their order information.
There is a spot for Billing information, a PO number and a brief description etc...
Shipping information
Form will not submit without certain defined fields.

What we could work with...
Anything that would email the order to us with their contact information and a comments field that was at least a little in the way of customizable fields and descriptions.

I'm sure we can't be the only ones facing this situation. Thought I'd share so the dev's could see a real life example.


EDIT:
Along the lines of Print this Page have an "Email this Page" that then asked for their billing information and sent the email would even be good. I could at least talk to them on the phone and get the order.

Could you use an online form, that way all details could be sent to you or printed out and sent.?

Would it be possible for the contents of the basket to be emailed to the registered email address ?

An extra button in the basket that allows it to be sent rather than finalising the checkout procedure ?

Sorry but no. That would require quite a bit of re-coding to make something like that work.

Would like to add HUGE support for this totally offline payment processing option. I would have happily used this for 2 clients by now, and a 3rd coming up, if this was an option. I love how easy it is to show clients to use the CoffeeCup themselves once its installed and set up for them, and they love it too, but I was stuck with Zen cart...