This plugin allows to easily create as many buttons as desired that each one can insert into the editor the HTML snippet that you want.
More info and a running sample in this blog post.
Licensed under the terms of any of the following licenses at your choice: GPL, LGPL and MPL.
HTML Buttons version 1.0:
1. Extract the contents of the file into the "plugins" folder of CKEditor.
2. In the CKEditor configuration file (config.js) add the following code:
config.extraPlugins = 'htmlbuttons';
3. Create a "htmlbuttons" entry in your configuration specifying the buttons that you want to create (check the included doc or the sample page)
4. Add those new buttons to your toolbar.