Warning, PNG experiment, this slides template will not work with IE6/Windows. It does work with IE/Mac and Mozilla/Mac&Win. Well... didn't somebody recently said that a Mac is a great presentations computer? This is another reason.
If you download this template you'll be able to change the background color of the slide simply editing the "bgcolor" inside the <body> tag at the beginning of the template. All soft shadows will gracefully blend to your background color.
PS: Want to have different templates for different sets of slides? Simply duplicate the #template.txt file from the /slides/ to the /slides/presentation/ folders. Very UserLand .