If you jump land, then jump again in a configurable amount of time your second jump can propell you further and higher.
This was a request by LuigiPenguin here: http:forums.bukkit.org/threads/when-you-jump-2-times-in-a-row-the-second-jump-is-stronger.284291/
Running: true Reaction_Time: 0.5 Upward_Velocity: 0.5 Foreward_Velocity: 0.3 ##Running: true - Means you must be running to perform a double jump ##Reaction_Time: 0.5 - The time in seconds you have to make your second jump ##Upward_Velocity: 0.5 - 0.5 allows you to jump over 3 blocks on your second jump ##Foreward_Velocity: 0.3 - 0.3 gives you a little push forwards on your second jump (sorry for spelling forward wrong)
To reload the config, type /Mario the permission for this is Mario.Reload
The permission to double jump is Mario.Jump
I have no plans at the moment, but I'm open to suggestions.