Preloader ‘replaces’ the systemmenu (it’s not really replaced, its main.dol is just renamed) with a simple loader which allows you to automatically load the HBC, a .dol you can install from SD or the systemmenu. It also allows you to use simple patches on the systemmenu.

Warning: This homebrew application will brick your Wii if you misuse it!

http://wiibrew.org/wiki/Preloader