Coral Dark is a free responsive theme with one-column or two-column layout, and built-in slideshow. The theme is optimized for SEO, and suitable e.g. for a portfolio gallery site or a photo blog that can be spectacular with its dark, black background. You can find a demo site here: http://www.coralthemes.com/demos?theme=Coral-dark . More info can be found here: http://www.coralthemes.com/product/coral-dark-wordpress-theme/ . Further customization options are available in the pro version: http://www.coralthemes.com/product/coral-dark-pro-wordpress-theme/ .