This week I needed to automatically size the height of an iframe to the height of its contents. After a bunch of Google searches I came across this post from Nathan Smith here; It used jquery but applied the auto height to every iframe on the page, I could not use the code out of the box and so the 'jQuery iframe auto height plugin' was born. I made a few slight changes to the original code and wrapped it in a jquery plugin.
Download from github
http://github.com/house9/jquery-iframe-auto-height
see the README file for usage