My server is called Sky Islands and has many floating islands which if you fall off, you'll die if you don't have infinite health. please make a plugin for this.
http://forums.bukkit.org/threads/god-mode.679/ I am working on it, but at the moment, bukkit does not support everything needed.
The plugin, found in my signature will do just that. I just updated it to work with #186, and so it registers all damage events and cancels them. That includes falling.
Good that's the method I used but it wasn't working then. But I have to port my other plugins first to wrok with command interface .)