McMMO is an open source plugin for the Minecraft multiplayer server mod Bukkit that is currently under development by Nossr50 . This plugin allows for an RPG-like experience to exist in the world of Minecraft complete with experience points, special powers, parties, PvP and more, visit the following website for more detailed information on Mcmmo, it's a great thing long ago that came and went through Ecc's History! ;D McMMO Wikipedia: http://mcmmo.wikia.com/wiki/McMMO_Wiki
Yeah, at certain bench marks you gain a special abilities. Example: Double drop rate. If you used the link I provided all of this information is provided to you with a click of a button.