InitialBootVideo demonstrates how to use the InvbXxx() routines to write directly to the VGA registers to display a message.

SysenterHook hooks the SYSENTER instruction so you can see the user-kernel transition.

RebootThroughKeyboardController demonstrates how to write to the keyboard controller to reboot the machine.  A user mode equivalent is UserModeHardwarePortIO.

LoadImageNotify demonstrates how to determine when an executable image is loaded into memory.  This is a really bad way of obtaining this sort of information as the OS provides official mechanisms for this sort of stuff.