Joist - Joist is a mobile application to manage estimates, invoicing and accounting for contractors.
Worksnaps - Worksnaps is a unique service specifically designed to track time for remote workers, telecommuters and freelancers.
Estimates App - Quick Estimation & Invoicing App. iOS, Android, Windows & Online @ https://estimatesapp.com/
Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.
Invoice Ninja - Invoice Ninja is a free, open-source solution for invoicing and billing customers.
OfficeTime - OfficeTime is a time and expense keeping utility for Mac, PC, iPhone and iPad. We also offer invoicing and reporting in an easy to use UI.