I've got an iframe within a document which the user can navigate around the internet with.

How would I use javascript to get the address of what is in the iframe and use it in my master document?

For example, my page loads with an iframe in it which loads up with SitePointForums.com. The user clicks through some links to an article they are interested. They then hit a "SAVE" button on the master page that the iframe is in, which in turn gets the current page in the iframe and does some processing in the master document.

Any ideas greatly welcome.