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.