Events in Google calendars form the base for bills, to be completed with rates, text and other items. The program outputs bills in PDF format, which may be mailed. The program offers a simple debitors/creditors accounting.
AutoVat provide a tool to freelance workers for invoice and bills management. The tool can generate the VAT form filled to present to the local tributary agency
JRPT is a library of JAVA objects and generic JSP files which enables the report creation offering many features at no programming cost. The package contains doc with examples of reports and their implementation in JRPT.