WP Super Edit & Some WordPress TinyMCE Notes
Discussion on wp-hackers centering around a simpler api for creating simple buttons.
There’s an example to add a quick button to TinyMCE at:
Someone suggested to combine that a simple button api with the shortcode api to create a simple visual editor button api. Probably way to many use cases to cover, but it is an interesting concept. Some groundwork exists in the Super Emoticons code for WP Super Edit.