If I have trouble concentrating on a 30-inch panoramic monitor, I can't imagine myself in front of the eight monitors the single-slot Matrox M9188 PCIe x16 graphics card can drive, each at 2560x1600 pixels.
The $US1995 Matrox M9188 comes with 2GB of video RAM, and works with Windows 7, Vista, XP and Linux. It can be combined with a second one to form a seamless desktop across 16 monitors. Apparently, this is perfect for "energy, transportation, process control, financial trading", and making your head explode. [Matrox]