Wikipedia
AppZapper is an application for Apple's Mac OS X developed by Austin Sarner and Brian Ball.
The software is an uninstall utility which extends the method of uninstalling in Mac OS X, which is dragging the application one wants to uninstall to the trash. By dragging and dropping an application to uninstall in AppZapper, the application searches for additional files residing in directories other than that of the original application, such as preference files and package receipts, the user is then able to select unwanted files and delete them.
Apart from the core functionality of AppZapper, other features of the application include a safety system which protects system files and user designated applications from being deleted and a log of uninstalled applications.
AppZapper is available as Shareware, which will block itself after "zapping" five applications. The current version 2.0 only supports Mac OS X 10.6.2 or later. The old version 1.8 of this software can run on Tiger and Leopard.