If like me you run out of screen real estate while working then this will help. Especially if you happen to have a spare computer lying around.

For me it was simple. Two Apple Mac laptops and a 21″ flat screen monitor on the desk controlled with one keyboard and mouse.

Using external monitors to gain screen space is common enough especially if you use a laptop as a desktop computer. Plug in the external monitor and the Mac detects it and extends your desktop. Select the arrangement of the screens, external to the left or right, and whether you want to mirror the desktop or spread yourself across both screens and away you go.

But suppose that still isn’t enough, these days you may want your social networks open in a browser so you can keep up with all your friends. Have a Twitter client running, Instant Messaging and Skype all take up valuable screen space.

The answer is another screen. But most computers be they desktop or laptop will only support one extra screen. So here is where that spare one comes in.

With me it’s my elderly but still perfectly serviceable 15″ G4 Powerbook running Leopard, alongside a 15″ MacBookPro.

How to do it?

Get a copy of Abyssoft’s free Teleport application and install it on both machines.

Set up is almost automatic but there is a fairly comprehensive FAQ in the disc image. And if both Macs are logged in to the same .mac (mobile.me) account, encryption is enabled by default.

Once activated the additional machine appears in the Teleport preference pane as another screen. Drag it to position it left or right of your main screen and as you move the mouse cursor to the edge of your screen it magically appears on the other machine as if it were attached, in the same way as it does to your external monitor. And you can then type into any applications on that machine with your main keyboard, and drag and drop files between machines.

This works over a wifi or an ethernet network.

And that’s it. Download and set up took me less than 5 minutes.

Moving the computers around and polishing away the several months worth of accumulated dust, crumbs and coffee stains on my desk took a while longer.

If you use Windows then Synergy is a similar application with the added benefit of being able to control Mac and Windows PC’s from one keyboard and mouse.