Passing Data from Parent to Child

I need to open a popup window and click on a hyperlink. The value from the hyperlink will be send back to the parent window.

I manage to open the popup window with javascript but don't know how to do the hyperlink in the child window and pass the value back to the parent window.

Can someone help? I did a search on this topic already but can't get a clear cut example. Do I need to use session variables?

http://www.vbforums.com/search.php?searchid=188668

Thank You