Adds robust billing and invoicing functionality to your WordPress site. You can easily create, edit, and send customized and itemized invoices to your customers without leaving your WordPress control panel.
How it works: you create an invoice from your WordPress installation’s admin section, an email with a brief invoice description and a unique link is sent to your client. Your client follows the special link to your blog, where their invoice is automatically displayed for them. After reviewing the invoice, your client pays their bill using a credit card or PayPal account, and you are immediately notified.
Since WP-Invoice 4.1.0 there are two new options in Business Process tab. (image at right)
Unified Page template gives you ability to have good looking invoice in any theme. And Client Dashboard shows list of all invoices for particular logged in user. Also Client Dashboard available for not logged in user, but with particular link.