I am surprised that no one suggested this plugin, I don't know if anyone did, but it would be awesome for someone to make a firework mod for Multiplayer!
There are already one. Search next time please. Link: http://forums.bukkit.org/threads/fun-tntfireworks-v1-1-shoot-those-fireworks-1000.30594/
Someone else did suggest it btw and I was just about to finish coding my firework plugin before I saw this thread XD