Let me start at the end - the idea isn't actually original. I remember Compuserve offering a similar service around the late 80's! I agree this all succeeds or fails based on execution.
> ... make sure you're doing address cleansing for the extra postage discounts.
Yes, this is actually addressed in our FAQ - we do address validation.
> Make a utility print driver so I can "Print To Postal Shout" -- this is VERY easy to do, at least on windows...
Could you please elaborate on this? I was always under the impression that building print drivers was a very expensive undertaking.
> ...Upon completion, create an XML doc (or similar) and call a web service ...
We actually do this now with our Word add-in which makes it easy to submit letters to distribution lists. Instead of running a mail merge in Word, the document and list are uploaded via Web Service.
> ...If you could somehow incorporate electronic signature / notary / SOMETHING into the documents...
This is very forward-looking at this stage of our project. I'll keep this in mind for later.
> Offer stationary / letterhead for the customers to design and use...
Great idea! With digital printing it's possible to print letterhead on the fly.
> You could offer discounts on the actual costs if the user was willing to have ads printed...
We haven't been successful in generating additional sales from similar initiatives in the past. I'll need to revisit this option.
> target Salesforce.com...
We do this with our postalmethods product, but haven't been diligent enough in execution. Will need to put more energy into this.
Thanks for all the suggestions! It would be great if you could clarify on the printer driver question above.