Adobe AIR Time Tracker Application: Klok
Adobe AIR, as it is no longer beta, will be more popular for sure.
Klok is another great Adobe AIR application which is built for personal time tracking. Projects, sub-projects (tasks) can be defined and can be attached to a customer. You can even make a "start & stop" to calculate the time of the task you worked on and Klok automatically adds it to the timetable.
Klok's UI works with the drag'n drop logic in general. You can send the items to the trash, manage the timetable and the projects hierarchy easily with dragging and dropping the items.
Klok is a very handy and easy to use application for freelancers & other individuals who want to keep track the time of tasks and projects they are working on.