iRatchet

iRatchet is an Invoicing and Billing app. iRatchet is written in Objective-C/Cocoa and uses CoreData, Spotlight, MobileMe, AddressBook and iCal integration.
iRatchet provides most of the features and functionality common to most billing and Invoicing apps (tracking hourly and fixed entries, multiple clients/projects, timers, pdf output, emailing of invoices, etc.), while excelling in workflow, mileage tracking, Web integration and ease of use.
This version has support for high precision calculations, storing country codes/currency codes on a per client basis, and a host of enhancements designed to assist those who have customers in various countries.