Is it possible to drive 2 monitors from a video card that's designed for one?

Here is the situation. I've been given a PC at a client site. It has a single monitor, however, I'd like to have another one since my work would go much faster.

I've been told that, no, I can't add another video card. But I can plug into the box anything external. So is there an external device that I can buy that would allow me to add the extra monitor?

There is the Matrix DualHead2Go and TripleHead2Go. They take the video card's output and split it to two monitors. If I recall they are rather expensive (a couple hundred bucks). So you end up running the monitor at 2048x768 and drive two 1024x768 monitors. You will be limited what resolution you can run by the graphics card.

You may use a USB 2.0 External Graphics Card - not really high powered 3D acceleration, but sufficient for normal office use.

One option would be a mini USB monitor such as the one from ThinkGeek. Another possibility is to use MaxiVista, but that requires that you have another desktop or laptop. But these are not ideal; a budget video card replacement would still be cheaper, and possibly easier.