A few months back, I released my responsive theme framework. It's 100% GPL, 100% responsive (including drop down menus), and is sold alongside what I call "Child Theme Skeletons" that alter the structural CSS of the framework in ways that give you a head start on new, unique designs. There are no design options... it's a true framework.
There are too many features to list here. Check it out at Volatyl Themes and let me know what you think.