Defining methods for a plugin
I'm not very confortable with the proposed solution to add methods to a plugin. According to
http://docs.jquery.com/Plugins/Authoring, you should use the pattern .plugin("method", options).
Why not creating a generic api plugin to be able to use this structure:
var api = $(...).plugin().api();
api.method(options);
The generic api plugin should just return this.data('api'), and the plugin developer would be responsible of setting this.data('api', methods) when necessary.
Regards,
G.