Scott Duncan
Mister Supernumerary is my personal favourite. Dean Clifford is fond of the very accurate "Mister Unauthorized Administrator".
When I am feeling particularly hostile I'll reverse the Gender designation. If it is a woman, I will use Mister, and if it's a Man, I'll use "Miss". :D
Derek Hill said it best (I Still can't believe I'm typing that); Drop the "Your Honour". They are simply "YOU".