Kensington has a lock on the notebook security market to the point that every laptop I have ever seen has a Kensington lock port on the side to allow you to lock your laptop to the desk to prevent theft. The company has taken the laptop lock that is has sold for years and made the thing easier to use so people are more likely to lock their note books down.
The new Kensington lock is called the ClickSafe. The part of the locking system that actually plugs into your laptop is the same as it always was and uses the same common locking port. The notebook portion is a little metal locking tab that goes into the Kensington lock port on your notebook and twists. It leaves a rounded knob sticking out of the side of your notebook.
When you need to lock the notebook down for a trip to the bathroom all you have to do is press the locking side of the ClickSafe to the little notebook nub and the notebook is secure. The cable for the ClickSafe lock is breakproof tempered carbon steel and the lock on the cable has thousands of possible combinations. The tumbler key is also pickproof. The home version of the ClickSafe lock is $49.99.