When the GeForce 7900 GTX isn't enough and you want to use up even more power, consider taking a look at nVidia's $17,500 32x and 64x SLI Quadro Plex. Featuring configurations from two Quadro FX 5500s at the lowest end to 4 GPUs and possibly more at the higher end, each of these bad boys is also equipped with 512MB or 1GB of GDDR3 per core, giving you a graphics powerhouse perfect for any hardcore developer. The "Model II" can broadcast HD content, and both of them are capable of pushing a lot of video data. Even if you could afford such a device, it would be rather worthless for gamers. But for a small graphics development or animation company, maybe even CAD and engineering, it could be your dream:

The machines are controlled from a PC or workstation - 32- or 64-bit, Windows or Linux - connected across a network. Nvidia reckons the boxes will interest not only content creators but folk doing scientific modelling and simulation work.
These machines are slated for a September release.