RescueTime is a useful tool for tracking your computer time, but it would be nice to get constant real-time feedback so you can see your scores plummet as you surf Facebook all day.
I hacked together a simple Windows application that lives in the system tray and shows your RescueTime productivity, updating every minute. You can get it here. You'll also need to install Python and PyWin32. You also need to enable a RescueTime API key here and then add that key on line 16 of productivity_feedback.py. If you want the application to run all the time, create a shortcut and set it as a startup task.
Yeah, I didn't make it easy for you. If I get a chance I'll put together a simplified cross-platform version.