Yes, there is.
It depends on which "skin" U are using to view the sight (there is a detailed post on skins here: 3 Different Skins/styles/themes ) - There are 3 different skins to the website.
My fav, Hexfluid is the Orange and blue colored skin. The "Mark All forums Read" is at the bottom of the main page.
On the dark colored skin (black and grey - it's called "Backslash Fluid" - U must click on the drop down menus at the top of the main page - Click on "Quick links" - U will find it there.