Grindstone 

Optimize your working process by tracking the time spent on various projects. Create a task by setting a name, an estimated duration, a due date, a completion date, an assigned rate and add comments. Generate graphs and charts, copy your data to the clipboard and export it in various formats.

Grindstone is a program that gives you unparalleled time tracking accuracy effortlessly. You can quickly and easily control timing functions, or change the task you're timing. You can add to each task a name and potentially an estimate, a due date, a completion date, an assigned rate (for billing calculations) and your notes.