Social Source Commons

The Gnome Time Tracker is a to-do list/diary/journal tool that can track the amount of time spent on projects, and, among other things, generate reports and invoices based on that time. It's being used it to keep shopping lists, organize ideas, track bug reports, keep a diary of activities, do some blogging, provide weekly status reports to management, and even as a consultant billing system.

Full-featured time tracking tool for managers and employees, with paid and free versions.