May we should start a list of event handlers/wrappers. Obviously there will be a lot of them, but maybe try and get the basics down. Then we can try to get them interacting together safely.
Have a look of dotclear website, the plugin architecture is small and nice. You have to manage event, but also preference panel, persistance, and little thing like i18n, icon, and templating (with widgets).
I haven't used JSON before, only AJAX requests, so I'll be off to learn how it all works. Don't worry about the stylesheet, as long as it is functional that is all we need for the moment.
JSON is just a serialization, with a javascript syntax. From javascript you use it like ajax, with a callback, but without XML parsing.
M.