Advanced and Basic Template Editor.

Basic Template Editor - For those admins with limited php/html/css knowledge - can change basic stuff like background image, upload header image, upload icon images etc.

Basic Template Editor Example: http://i.d.com.com/i/dl/media/dlimage/19/86/10/198610_large.jpeg
or
http://www.topsoft.com.au/images/Document-Template-Editor.gif

Advanced Template Editor - For advanced users where there's no limit to level of editing html/php/css to get the look they want. Also have file manager to upload images to be used within the template. Ideally viewing the changes they make "live" as they go.

Advanced Template Editor Example (Wordpress Theme Editor):
http://wpcandy.com/wp-content/uploads/2008/11/wpthemeeditor-regular.png