This is actually an easter egg hidden in the Mozilla Firefox.  You can open multiple browsers inside Firefox by pasting the following line into the address bar:-

Split Screen is an extension of Google Chrome which gives you the ability to browse all the open webpages through a single window.

Iptools.com is a site which gives you free information about various issues related to IP address.  It is even more better a site of Network Administrators who need to have access to various critical information related to Internet Protocol (IP) address.