Bukkit

Handles all player administration:- Bans, kicks, IP-bans. Stores locations of bans, and multiple ban reasons.

Give certain people the ability to log on to servers when they are full!

Add potion effects to any player with custom modifiers!

Have your players call a vote to perform any command you like! It is fully customised!

Schedule commands to be run from a file in an ftp server:- web based commands!

Jail bad players for a specified amount of time.

Wear anything you like on your head!