I suppose that the functionality asked should be hard to do, but so great..
Would it be possible to plug actions (http://yoursite.com/admin/config/system/actions) with forms ?
I explained from my need but of course it has to be open.
When a authentified user submit the form, and for example thick a box, this will start for him a subscription. This subscription is identified by a role.
The idea is, when the user thick a box and submit the form, his role is updated. Same thing when he puts other email address, the role of account associated can be updated as well.
I hope to be clear.
It could be so great, as the form could be not only a contact form, but a subscription form for services, events etc.
Thank you !