Ability to add custom fields or custom forms in the Ad-hoc New Task Area

It will be nice to be able to add custom fields or a custom form to the Ad-hoc New Task Area. Our case scenario is whenever we are creating a new simple task, on behalf of somebody else (an Executive), that does not require a project, we would like to fill out who is the requestor and his/her department. It could be set up in the Layouts set up area