As easy as it sounds, you turn off all engines, sensors and weaponary in your ship, disabling everything, and also you disappear from HUD.
It could be use for stalking and spying, to escape stealthly from danger o to do repairs in your own ship (another suggestion).

Nice idea, but it has been suggested before:

http://vendetta-online.com/x/msgboard/3/2489#254093

Indeed, also

PLEASE READ PRIOR TO POSTING A SUGGESTION

All the threads you started are to be found in there.

I red every suggestion posted here, but I saw ship shut down as a addon for cloaking system, not a normal and functional shut down.

Apologices for the inconvenients.