ALL BELOW UPDATED AS OF 1.0.4

Simple and powerful standalone plugin or hook into it with your own plugin.

OTHER PLUGINS
Check out my other plugins which make up a suite of compatible plugins.

Upgradable - http://dev.bukkit.org/bukkit-plugins/upgradable (Add upgradable weapon, armor and tools)
Skills - http://dev.bukkit.org/bukkit-plugins/mc-skills (Add a GUI-based leveling skill system)
Special Arrows - TBA (Allow players to unlock special arrows through a simple GUI system)
Stunned - http://dev.bukkit.org/bukkit-plugins/stunned (Increased difficulty by allowing players to be stunned by mobs)

SERVER OWNERS:
You can allow your staff to "stun" players at a location. Can be used to punish players or integrate with custom mobs to stun players. Players cannot interact with the world like break blocks, move, attack, use Enderpearls, teleport. I'll add some config options to make each a toggle later on.

To give a player permission to use the commands, give them "stun.allow" permissions. You can change this permission node in the config file.

COMMAND LINE
/stun PLAYERNAME
/stun PLAYERNAME SECONDS
/stun reload

MOB STUNS
As an added extra, I have allowed you to determine if mobs will gain the ability to stun players as well. It is OFF by default, so if you want this functionality, since go into the config and ENABLE by setting 'mob_active: true'

You can then set whatever mob type to 'true' and set how long they will stun a player for. If you set 'mob_random: true' it will stun player for 1 to whatever seconds you list.

PVP STUNS
You can turn on the option to allow Players to stun Players during PvP. Same rules apply, set the chance for a stun and duration as well as deciding to randomize the duration.

DEVELOPERS
Developers can easily hook into Stunned and use its friendly API.

Simply add a reference to the Stunned.JAR
Create a reference to the API: StunAPI stun = new StunAPI();
Then just issue the command stun.start(); (starts the tracker - stun.stop() to stop it)

I'll polish up the methods accessible below but most are self explanatory. You must pass the Player UUID to the methods.

stun.add(UUID, Int) - Add a player to the stun list, Int is the duration in seconds
stun.remove(UUID) - Remove player from stun list
stun.isStunned(UUID) - return boolean if player is stunned or not
stun.getLocation(UUID) - returns location the player was stunned at
stun.message(UUID) - tells player they are stunned
stun.process() - forces an update of stun list (happens every second automatically)

Configurable options will be released with a future release based on feedback.

Config File