Marxio Timer is a totally free application (though the authors appreciate a donation) that lets you program set tasks and actions at a set time.
Some of these actions that you can run with Marxio Timer are: shut down the PC, suspend it, block the desktop, view a set text (like a reminder), make a sound or music play, run an application, minimize a window/program, etc. The activation of all these tasks doesn`t have to be at a set time, as you can program a countdown timer instead.
For any of these actions you must know the password you previously configured in Marxio Timer.