The Sapphire VID-2X offers you a new way to utilize multiple displays without needing a graphics card capable of powering a resolution of 3840×1200.  It can both clone and stretch your desktop and is Plug & Play with no software or drivers to install, simply plug it into a dual link DVI port and it is ready to go.  At an MSRP of $180 it is less expensive than an SLI or CrossFire solution though it is limited in performance by your GPU.  You might be able to stretch your game across three monitors but you might find performance suffers somewhat.  Instead you can consider this a way to get multiple monitors from a single NVIDIA GPU or a way to avoid an active DisplayPort adapter for a Radeon card.  HiTech Legion has several videos of the VID-2X in action which you should check out.

"Sapphire’s VID-2X is a plug and play compact device that was designed to extend your existing monitor into one large field of view, in effect, tricking the system and allowing you to add two additional monitors to your system from just one display port, be it a laptop, netbook, home computer, or office PC. The VID-2X from Sapphire accomplishes this without you having to install any software or drivers. In addition, the VID-2X will make use of the video card installed and, without using system resources, maintain a resolution or output in clone mode of up to 1920 x 1280. The VID-2X offers several connection options using your existing cable option of DVI, with cables included, and once installed, will double your field of view. The Sapphire VID-2X will also adapt to VGA or HDMI display ports with adapters you may have on hand with your existing system."

Here are some more Display articles from around the web:

Displays