Lockette:

So what is Lockette?
Lockette allows you to protect chests, doors, furnaces, enchantment tables or cauldrons from people using them & destroying them when they have been placed in the world. To protect these you need to use a sign and place it 1 block away from the container, either above or next to it.

Lockette Development Page: http://dev.bukkit.org/server-mods/lockette/

So how do you set up the sign?

The sign needs the following code to privatise the chest/door/container:

Sign first Line: [Private]

Once this has been wrote, the sign will automatically stick to the chest or next to the door & place your name on the second line. This has then privatised the sign for your use only, nobody can destroy, open or use the container unless their name is added on the 3rd or 4th line.

Adding additonal people:

If you want to add more people to allow permission for them you can add their name to the sign. To do this you need to right click the sign & then enter the following code. The code will also come up in the chat box if you need extra help writing the code:

/lockette [Line number] [UserName]

This will then add the user to the line number selected, for example:

/lockette 3 BlinkyHD

This would add myself to the 3rd line.

Adding a lot more users?

If you need to add several users (More than 3) there are two ways in which you can do this, you can allow everyone to use the container, however you will have the main permissions or you can add an additional sign to left or right of the previous and use the code [More Users].