Check this out:
(It's not built for IE8 and down. I can add some scripts do so, I just haven't yet)
Scale the browser back and you'll notice the UI shifts at 4 resolutions:
1000px - full size
720px - ipad/tablet narrow
480px - smart phone wide
320px - smart phone narrow
I'm still building it, and will probably add it to the WP themes page when it's done. Just looking for feedback.