I have been looking everywhere for a device like this one!
My main problem is when I'm sitting in the living room and I want to watch a film that is on my laptop I usually plug a VGA cable into the back of the TV. However this means I can't use my laptop at the same time as it needs to sit down by the TV. This little box solves that problem.
While this may not be its intended purpose, I plug this little box into the back of the TV and connect it to my home network. My laptop (after installing some software) discovers the StarTech box on the network and treats it as an extra monitor. Any film I want to watch I drag onto the second monitor (being my TV) and play it there while I'm free to use the laptops main screen for work.
Any computer on your network can use the StarTech box as an extra monitor. It also has some USB ports built in which means you can plug a mouse and keyboard into it and control what ever computer that is broadcasting to it from the TV.
If you do use this device and you connect your laptop over wifi ensure you have a fast wireless network (more than 54meg) or you'll see some blocky video.