CHALLENGE: Grab URL of iFrame!

Willing to pay $100-$200 for a solution! This may seem trivial but apparently it is not so. All that I need to do is grab the CURRENT url within an iframe that is located on a wepage on my server. So bascially, something like this: 1. User visits (someone_else's_site).com that is contained within an iframe on (my_site).com 2. User clicks a button OUTSIDE of the iframe 3. The current url of the iframe is submitted to me. You can use any method at all to solve this problem. It seems like if the user used the 'Save Page as' feature in Chrome, then the current url of the iframe would be not be saved within [login to view URL], however it would indeed be saved within the folder/file (saved_page_files)/saved_resource.htm... so perhaps someway to get this so save to the server instead of locally might be a lead! But any other way you can figure it out is accepted too!