Bukkit

There are 3 powers:

• Hard
• Legendary
• Ultimative And many actions. Now you can set, which actions will happen if you use /power hard/legendary/ultimative and some actions are configurable too (example: you can set the potion, the player will get, if you have this action on true). Also you can bind a power to a block, set a cooldown, set the messages etc.. Example with a RPG Server:
• Wizzard can use power hard
• DragonMaster can use power legendary
• ShadowMaster can use power ultimative

If you will use power hard:

• A explosion will be created
• Other players near you will be striked
• You will get a potion effect: SPEED
• some more actions

If you will use power legendary:

• You will shot arrows around you
• You will get armor
• You will get Weapons
• You will create a firering around you
• Some more actions

If you will use power ultimative:

• You will spawn zombies around you
• You will poison players near you
• You will be healed
• Some more actions

Then there could be a cooldown:

• Power hard can only be used every 25 minutes
• Power legendary can only be used every 30 minutes
• Power ultimative can only be used every 20 minutes

You can set a lot of more things if you want... This was only an example how it could be.