How to view ALL Unread posts rather than just the ones since last visit

I own another forum and a very useful link is to view all unread topics rather than just the new posts since the last visit. For example, there might be something interesting going on that I did not get a chance to read, but as I return to the site it is now not visible since nobody responded since I left.

this is a link that will show ALL unread topics regardless of the last login (viewing) time:
http://www.canonrumors.com/forum/index.php?action=unread;all;start=0

pierre