HTML Editor Reloaded plugin by uniquemethod allows you to add your own custom buttons to the HTML editor toolbar. For example, to add an H1, H2, H3 button to make adding headers to your content easier. Add as many buttons as you need.
You can easily enable a fullscreen mode for the HTML editor by clicking on the ‘fullscreen’ button.
And it adds an ‘enable / disable tabs’ button for tabbing single and multi-line text directly within the HTML editor. You can easily indent using the tab key or unindent using the (shift+tab) key combo.
Download and info: http://wordpress.org/extend/plugins/html-editor-reloaded/