Thank you for the quick response. I am indeed referring to collaborators, when I say "ability to add/change/inquire/delete user accounts and passwords (on the fly) via API."
Basically, I can write the glue (API calls) to have our system stay in sync with external services required for (or offered to) our customers. I already use API's to integrate other outside services; everything from establishing their domain name, to creating DNS zonefiles across 5 servers, to creating their virtual hosting directory (site) on a web cluster, and so on.
I would like the ability to create collaborator accounts for customers, on the fly (via API)... and to manage said accounts via standard endpoints... like "/collaborators/list" and "/collaborators/add" (delete, search).
If I were only able to export a site via API, that would be a great start. Next, the ability to add collaborator accounts would be great... I can even live without the others.
Food for thought - if it were possible to add "triggers" (like PayPal does with it's IPN - instant payment notification, where they POST to the designated URL each time a transaction takes place) to WebFlow sites, to let us know when a site has been updated in WebFlow (and thus should be exported - "published"), then our server would know it's time to "grab" the site via your export API, and publish it... no human interaction necessary (e.g., export zip, upload using winSCP, ssh to server, unzip into customer's web directory, make sure permissions are correct, soft-restart apache, etc).