Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.
InvoicePlane - Free and open source invoicing application to host on your own server.
TimeCamp - Simple and robust time tracking app to help you stay on the same page with your team while working from home.
Invoice Ninja - Invoice Ninja is a free, open-source solution for invoicing and billing customers.
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.
Billdogg - Beautifully simple invoicing for freelancers