For some odd reason, cats seem to like walking across computer keyboards. To discourage this behavior, programmer Chris Niswander created a program to detect a cat on the keyboard.
Dubbed PawSense, the program analyzes keypress timings and combinations to distinguish cat typing from human typing. Once PawSense detects a cat, it triggers a popup window that locks the keyboard, preventing the animal from wreaking havoc on the operating system.
To further discourage a cat from walking across the keyboard, PawSense can play an annoying sound to frighten the cat away. Surprisingly, PawSense has worked for many people who claim it has kept their cat away from the keyboard.