I just saw these plugins some where im not even entirly sure if there plugins and not mods.

ComputerCraft www.minecraftforum.net/topic/892282-145-computercraft-147-now-in-color/

GuildCraft dev.bukkit.org/server-mods/guildcraft/
im not sure if it is the latest version

please check them out. im not good with understanding this plugin stuff but these seem cool. especialy guildCraft since its not like Factions