Tweaker4 is a WordPress theme by Arnold Goodway specifically built for those who love tweaking their own themes. Open, clean and quick-loading design with a wide sidebar on the right. Options page offering a choice between a dark or light layout, caters for all the post formats and also offers user support via a support forum.
Theme homepage: http://tweaker.co.za/free-wordpress-themes/tweaker4/
Download: http://wordpress.org/extend/themes/tweaker4