Good Riddles

Question: Those who make this item, don't use it. Those who BUY this item, have no need for it. But those who USE this item, never see it. What is the item?

Question: A grandfather has a broken grandfather clock that is off by a minute every hour (too fast). He figures out a way, while keeping it running at the same rate, to make the clock say the correct time twice a day.

How could he do this?

Question: Every night I'm told what to do,
and each morning I do what I'm told.
But I still don't escape your scold.

What am I?

Question: 500 is at my end and my start, yet 5 is at my heart.
The first letter and the first number make me complete.
My name is that of a king.

What am I?

Question: Everyday I stalk you all day long,
With every move you make, I never make one wrong.
I vanish twice a day with the sun's height and fall,
I will follow you anywhere,
even the bathroom stall.

What am I?