Bukkit

First public version

Features

• Stops players from referring themselves
  
• Doesn't allow players to use the /refer command, if someone else has claimed they were referred by this user. This is to prevent people from doing a "I refer you and you refer me" sort of thing.
  
• Doesn't allow users to say they have been referred by someone, if they claimed they have already been referred by another user.
  
• Customizable messages
  
• Customizable Rewards. After a certain amount of referrals, or every time a user refers a certain number of players. Currently, only 3 tiers are available.