I would like to add another responsive theme that was born in 2013 (it was born a couple of minutes ago, actually); the Nexus Twenty Eleven v3. Its based on the GPL Nexus Framework, and thus features front-end editing (including page builder, multi header, sidebar and footer), its responsive and has an advanced (LESS-like) color theme based on CSS variables and its free forever free for everyone! nexusthemes.com/twenty-eleven-wordpress-theme/

Many of interesting wordpress designs I found on bestforwebs.com/ … must see!