Little Brother is watching you but only when you tell him to: minimal task timer from Windows7 notification bar.
Select a single task at a time, from a simple menu accessible from the Notification Area on right-click:
It's simple to add, remove a project. And also to pause it for a given amount of time:
The real downside of it all is... well, that the output is pretty ugly. If you choose TimeSheet in the menu, you get this:
There's definitely some work that can be done there.