Its a start...

Could be better.

Adding sections such as : Paid Invoices, Unpaid invoices for ALL your clients would be great.

Also reminders would be very nice too...If you could tell this app to send you an email if an invoice is not payed in lets say, 3-4 weeks, that would be a very nice feature.

Adding labels to invoices (colors) would also be a good way to organize your invoices.

Its currently too plain and basic but has good potential.

Dpstatazz about Invoicing, v1.1