So you're following the latest trends in #web development and have decided to develop your new site with a #responsive design. You quickly realize that's kind of hard testing the site on multiple resolutions every time you make a change.
has a nice solution: http://bit.ly/ycYno9
A simple setup with iframes will show the same URL is four different resolutions.
Of course this doesn't fully replace testing on actual machines (and their specific browsers) but it will certainly speed up the initial development time.
If you want to host it locally, you can grab the html/js on GitHub http://bit.ly/xu39c5