Some of our sites are visibly FRAME based, with a Navigation Frame, and a content frame... Sometimes the content frame will get referred to directly by an external party, like a search engine.
If we were to load this content frame without the surrounding frames, then the visitor would loose any ability to navigate the site. So we detect when this happens, and reload the site with the intended content inside of the main site build:
Click here to see an example of this in action - You will notice that the relevant Main Page has opened up in the Navigation, showing the relevant Sub Pages too.
This function uses a Content Loader which is passed back into the TOP frame, it then passes the required information down into the frames so that the relevant page contents are shown.
You can use this functionality to your own benefit, along with SmartURLS to load a particular section of a frame based website using a nice friendly URL. An example using Minx's site is here: http://www.minx.co.nz/Where2Buy