I started working on a site recently using the Omega theme. In general, I find (once you get used to its ins and outs) Omega is a great theme to get a responsive Drupal 7 site off the ground relatively quickly. It comes packaged with all sorts of goodies, and is based (and includes) the 960 Grid System.
That said, occasionally you have to modify something, no matter how flexible a theme might be. In this case, I really wanted to move the Footer region outside of the #Page div. In this case. My reason for doing this was so that I could apply a solid background color and a box-shadow to the #Page div, and have the footer sit directly below it, against the Body background.
After hunting through the TPL files that the Omega sub-theme start kit includes and not finding what I needed, I turned to Google and found this post on Drupal.org.