HopToIt is a project mainly written in OBJECTIVE-C and C, it's free.
Fast time tracking for Mac OS X
Bring up the entry window using the menu bar or with the hotkeys shift+command+space or command+option+right arrow
Enter the name of your task to start tracking.
When you start a next task enter the name of it.
If you want to stop the current task without starting a new one enter ":stop"
At the end of the day type ":list" to bring up a list of the tasks you did today.
This is just the beginning - more features coming soon