Some client side mods are popping up for some of the plugins, and my dream, as a player and a mod coder (wanabe) who has no interest in modding the client, would be to have an "uniformized" client side pluggin for Bukkit mods. Something that would show the inventory, catch the craft table input, etc, or even having customized dialogs. It could be as simple as requesting a type of dialog, a number of slots and a title, etc. Something more advanced might allow to add block and item types to the clients remotely, etc. Custom dialogs and custom blocks might be enough for a lot of cool ideas to be implemented.