1) We need to be able to add items to an invoice so the client knows what they are paying for vs. receiving a subtotal.
Manually entering each invoice vs. adding from a list of saved items would be much more efficient.

2) Having an option of payment date on an invoice (i.e. payable in 14 days, 30 days, etc.)

3) Having email reminders sent to clients with outstanding invoices at 7 days, 14 days, etc.