The only thing I really miss in Invoice Ninja is a some kind of ticketing-system where customers can create tickets in their dashboard/portal or any place really (by including a form on any page of a website).
A priority system (low - medium - high) would be a great additional feature.
When customers create a ticket, both the customer and staff will receive a confirmation by e-mail.
If a staff member processes the ticket and wants to charge the customer for their request, one button could redirect the staff member to the page where he/she could create an invoice for the ticket/support request.
What do you think of this suggestion?