Hi Jason, re: plug-in gallery, see here for some links:
http://kyticka.webzdarma.cz/3d/moi/#PluginGallery

It is possible to set up quite a bit of custom UI in MoI currently but you have to edit some HTML files to make it work. The plug-in gallery is one example of setting up a custom HTML dialog that has some particular commands on it.

In the future I'm planning on having an easier way to manipulate the UI though.

- Michael