Invoices

HI All, What do you all use for keeping track of invoices? I looked at a few open source projects (including http://billing-software.us/) and it seems that there is not really a good Open Source Project out there for invoices. Am I wrong? What would be nice is a project with a good API that would allow other projects to use its invoice handling capabilities. It would be nice if it weren't designed for one specific situation. Have I missed the boat here? Is there a nice OS Invoice program that will do all this? Has anyone considered starting one? Thanks, -- Leonard Burton, N9URK leonardburton@gmail.com "The prolonged evacuation would have dramatically affected the survivability of the occupants."