Well I hadn't planned on making the entire site background dark... so it's hard to envision those themes surrounded by a white background.
Here is another site with themes: http://demo.phpbb3styles.net
On this one, just refresh the page to see a different theme
I haven't looked much, but after seeing a few, I kind of like Artodia Air Red
(though, with a white overall background, who knows how it would really look). This one also looks like it has a mobile version (plus!)