Often I am at a client site with my notebook, wishing I had a second monitor. Often I also have a tablet with me. Why couldn't I just use that as a 2nd monitor? Thus began the search. I stumbled across one solution called Splashtop.
It is super easy to setup. Install the Splashtop Xtended Display on the Android device, which can be found in the Google Play Store. On the notebook/desktop download and install Splashtop Streamer.
The two devices must be on the same subnet; yes the screen data is transmitted across the network, and is encrypted. The main machine must have an available display port; aka the ability to have a 2nd physical monitor. For instance one of my desktops has a dual head video card in it, with a monitor on each port, in this case Splashtop will not work, as both monitor outputs are spoken for. My test mule is a notebook which has the built in LCD panel and a VGA plug for a 2nd monitor. Splashtop works by spoofing Windows in to thinking there is a monitor plugged in.
On the mobile device, create a new connection, give it a name, and a security code. On the PC setup an account with Splashtop, create a security code that matches the one on tablet. At this point the PC starts broadcasting on the network for Splashtop clients. On the mobile device the PC's should populate in the Splashtop window, simply click on it to start the session. Volia....you now have two monitors!