This plugin lets the admin protect claim chunks.

This can be used to protect spawn, hotels, farms, PVP arenas,and other things.
Can only be used by OPs.

In-game commands are as follows:

/CHUNK HELP - Will display a help message outlining the following commands to the player who issued this command.
/CHUNK PROTECT - Will protect the chunk that the player is standing on.
/CHUNK PROTECT AUTO - Will protect chunks automagically as you walk around.
/CHUNK PROTECT OFF - Will stop protecting chunks automagically as you walk around.
/CHUNK UNPROTECT - Will unprotect the chunk that the player is standing on.
/CHUNK SHOW - The player will see a border around of all protected chunks within view.

To install this plugin, copy the plugin JAR file to your server's plugins folder.