Macaw
Macaw is a browser based code savvy design tool for responsive design, and produces both semantic HTML and no-fuss CSS.
Created by web developers and designers the product is built specifically with you in mind. The take into account fluid grids, breakpoints, full typographical control, and effects while allowing you to build them modular so reuse is key.
As of 17th January 2014 I’m currently downloading Macaw to take it for a test drive, more to come.