You know how in say, an address book app, you can hit the plus button below a field and it gives you another of the same field? It would be great to have that so you could have fields for something like, "children" and then have Child 1, with a plus icon to allow the user to add child 2, child 3, etc.
I suspect this could get VERY complicated depending on conditional stuff (I'd want to have other fields appear each time the person hit +), but it sure would increase the power of DTRegister.