I was quite busy the last months with creating my first responsive WordPress theme. Before then all my themes had a fixed width and were not a bit adaptive to the browser width. In times of tablets, smartphones and netbooks with thousands of possible screen sizes, releasing layouts with fixed width make little sense anymore.
Therefore it was time to shift to responsive webdesign in order to keep step with modern web development. I have tested and experienced a lot with mobile navigations, CSS media queries and all the other technical stuff required for good responsive webdesign.