With this plugin you are able to setup ores to spawn in a classic cobblestone generator! Each time a block spawns in a cobblstone generator, it has a chance to change into a certain ore. These chances can be changed in the plugin's config.yml file under "Probability".
Hey guys, don't freak out if this isnt working for you. The dev is working on getting the proper release published. He accidentally uploaded an old version.
(I'm his friend, I can assure you that this does work!)