AddQuicktag
This plugin makes it easy to add Quicktags to the html – and visual-editor.
Plugin Tag: add buttons
Post Editor Buttons Fork
This plugin allows you add your own buttons to the post editor's TEXT mode toolbar.
Post Editor Buttons
This plugin allows you add your own buttons to the post editor's toolbar.
XHE Quicktags
This plugin makes it easy to add Quicktags to the html – and visual-editor.