I've been looking for someone willing to start a plugin packed with it's own large number of customizable enchantments to add to the enchantment table. Directory of configurable enchantments! In the folder there will be an example file for a custom enchantment. It will list the possible spells that can be used on each enchantment, like Fireball, Freeze, Super Jump and so on. You can name the enchantment files to w/e you want. The config sample will also have extra options for adding configurations to the damage, distance, cooldown and more that I can't currently think off the top of my head at the moment. Custom Enchantments possibly shown on enchantment tables! I figured showing custom enchantments on the enchantment table will probably require client modification. I'm not sure if this is the case for just changing the numbers of how much EXP is required on each gibberish enchantment reading. Otherwise... If that's the case a custom menu in chat can appear when the enchantment table is clicked on by a player holding an enderpearl (The item used can be configurable in the settings) Enchantments are almost just like spells. These custom enchantments provide RPG-like skills like. Say I enchant FireBall III to my Diamond Sword. It will shoot fireballs whenever I swing it and so on. Of course fireball can't be placed on to armor so if someone attempted to create a custom enchantment for armor to use fireball it will just not show up in the menu OR instead of naming it Fireball it can be called Fire. Depending on what FIRE is enchanted on it will come with different effects. If Fire III was placed on any type of armor it will give resistance to Fire and possibly have Fire Damage towards an enemy successfully damaging you. As for weapons it will shoot a fireball. This is just an example, but I think it's a well worth idea. Hell it can come with custom potions too. If you'd like to discuss more about this plugin with me contact me on skype: phantom-index Suggestions to this idea can be taken from replies to this post.
This plugin basically has everything you mentioned and it's actually pretty fun: http://dev.bukkit.org/server-mods/magicspells/
Definitely check out Magic Spells as its the most mature, but as for new enchantments specifically also consider EnchantMore. It isn't a complete solution since you need another plugin to add the enchants to the items, and it doesn't have cool downs or other advanced features, but it does have more than 50 effects to choose from, including shooting fireballs (using the Sword + Blast Protection enchantment).
