On my website, I have a section for sharing links. When a user views the link, I want an overlay frame from my site at the top of the page.

This is a little hard to explain, so here is an example of a shared link:

http://shroomtown.com/index.php?page=link&id=1

When the user clicks 'View this link', they should be taken to the link, but with an overlay from my site at the top like this:

http://shroomtown.com/link_overlay.php?id=1

What is the best way to go about doing this?