how would you feel if every time you hit your borwser's back button while viewing my site you are redirected to http://www.dangerous-site.com/install_unknown_exploit?
wouldn't you be happy if you had a browser that won't allow someone to control it and to perform actions different from the action you want your browser to perform?
i mysql i'm happy that this is not possible and i don't see any reason why you need to change the behaviour of software running at your visitors' computers...
why do you think you need it?