I wanted to point out that I come from a web development background and I am used to having more control over layouts than the Visual Editor allows. When creating static pages, I would put html in the code editor, switch to the visual tab, and then save the document only to see the positioning of things change. I understand that WordPress is not a heavy duty CMS, and that the Visual Editor is set up to keep code XHTML compliant. By adding buttons to the Visual Editor by altering the TinyMCE.init parameters, I would break the XHTML compliance that is built in to WordPress. As a developer, it's time for me to learn how to do table-less layouts via css so my code and my static pages will retain XHTML compliance.