Only Popup Once

If you have a new window open up on your home page, it opens every time your visitors come back to that page. This is rude as well as very annoying thing to force onto your visitors. But, using cookies, this JavaScript can determine if the visitor has been here before, and only open a new window on their first visit to the page. The next time they come back, the script will read the cookie, identify them as a repeat visitor, and NOT open the window again. Neat!