A very useful Win32 program written by Steve Gibson in response to spyware which reports the user's behavior and information about them to a large, evil corporation. OptOut removes the responsible DLLs from the system, often rendering the programs that use them unusable. It's written in assembler and the first version of the executable, complete with GUI, embedded documentation and visual explanations was only 31K in size.

OptOut can be found at <http://grc.com/optout.htm> along with some helpful information about spyware. It is closed-source and coming versions will be commercial.