Bukkit

Allows you to fly!

Crafting:

Ok, so now you've got yourself a jetpack, but you can't fly yet! To do so, you need fuel (configurable, redstone by default). Press left mouse button while holding your new jetpack.

Charging:

Now you just equip it and fly away by holding SHIFT! The jetpack will drain the fuel overtime (configurable, 1 item/second by default). Your current fuel amount is being displayed on the sidebar scoreboard (assuming you have scoreboards enabled).