The shortcodes bar looks nice!
What about a settings page under the WP settings area to choose which shortcodes to be visible in the TinyMCE menu area (as more shortcodes are added that take more room then what is available in the menu area). Extra shortcodes can then be added to an icon drop down.
Other shortocodes to add:
- List post with 2 grid, 3 grid etc.
Width % or px.
Align left, center, right.
Height px or %
Take a look at http://wordpress.org/plugins/olevmedia-shortcodes/
Which has an interesting box that can also insert an icon as a kind of box heading.