*www.linuxsoft.cz/en/sw_list.php?offset=15&id_kategory=32
WebInvoice is there,gnucash will also?
*freshmeat.net/projects/stwebinvoice/
billing and invoice tracking
Online billing software will allow your business to track invoicing and allow your customers to view their invoices and online and easily export them to excel for printing or saving. Invoices can also be emailed to customers right from the online application for convenience and efficiency.
*www.billing-software.us/