This is in asp purely for the server side includes but could be in anything including plain html.
I had a requirement where the careers functionality was being handled by a third party, but my company wanted the pages to appear within their own site.
Added to this, the thrid party displayed the pages with their own version of my company's header, menu and footer styles, so the embedded one needed to not have this showing.
Also, the third party's pages were all different lengths, so the IFrame needed to resize it's height appropriately.(This is the tough one)
Check out the careers page.
In order to accomplish this,
you must have access to the code on the parent and the shild within the iframe.
This is taken from http://benalman.com/code/projects/jquery-postmessage/examples/iframe/ and expanded.
Review his stuff then see what adjustments I have made, like passing the parenturl on in the links and choosing the css based on the window target/location.
The 2 pages used in the frame are here: http://www.houghten.com/iframesizing/frame1.asp and http://www.houghten.com/iframesizing/frame2.asp