Choice is a free minimalistic WordPress theme, which allows you to change the color, sidebar number (1 or 2), among other things in an easy to use configuration file.
Link: http://www.themelab.com/2008/04/29/choice-free-wordpress-theme/
Demo: http://demo.themelab.com/index.php?wptheme=Choice
Download: http://www.themelab.com/downloads/choice.zip