Please focus on the application in the middle. It is a linux based and called Driftnet – the task of installing was easy in Ubuntu (did I tell you how I love apt-get?) What in the world is Driftnet?
Quoted from Driftnet website
Inspired by EtherPEG (though, not owning an Apple Macintosh, I’ve never actually seen it in operation), Driftnet is a program which listens to network traffic and picks out images from TCP streams it observes. Fun to run on a host which sees lots of web traffic.
In short – it is an image sniffer and if you placed it correctly/strategically in the network, you can see all the images passing through -or in other words you’ll see what everyone in the network are watching in their browser at that time in realtime!!
I read about it many years ago in Linux Journal and I think I have tried it once before so having the new mini-itx box with me now, I am recollecting all those interesting apps to be installed in this 60GB computer 
Use it at your own risk — don’t get caught sniffing images at your office’s network!
