We have been fumbling this idea for a while and we cannot find any other provider that has this service (or perhaps we don't know what it's 'officially' called).

Does anyone have any feedback on offering such a service. I would especially like to hear from anyone interested in such a service. Have any hosts tried this before and failed?

It's not about the money, it's about the time we put into it. I don't want to spend time scripting a control panel for these customers if the demand for the service is weak. However, in the past couple of weeks alone I have seen people on WHT asking for a similar service but probably had to get an actual web hosting account with lots of transfer and little $ (if they find a provider that allows it that is).

This service would be FTP-only with HTTP/FTP downloading and some other perks and features we have in mind

Any thoughts?