With a variety of playback systems available these days that can easily and flexibly power multiple displays, for many smaller productions and operations the main obstacle to driving multiple projectors or screens is a playback computer with more than two video outputs. Computers loaded with multiple video cards can still be expensive or need to be custom-built. And if you are running from a laptop, you’ve got the one out, and that’s it.
To solve this problem, several companies have recently released USB 2.0 to DVI-I adaptors. These are tiny, low cost (at around $130), and up to six can be connected to a single computer. As soon as I heard about this product I ordered one. My initial (non-show conditions) testing of the product has been impressive. The color depth is indistinguishable from a normal DVI connection to the naked eye, edges are crisp, and soft gradients remain nice and smooth. The only fault I can find with its display capabilities is a tiny lag in response time—you may want to avoid extremely high-speed imagery as inconstant fast motion seems to produce a bit of a stutter.
Other things to consider: the Mac OS X drivers were released just recently and may find issues with some platforms. Also, the claim about being able to connect six at once is principally dependent on your computer having multiple USB 2.0 controllers.
There are of course other uses beyond production display. I already know that where I will get the most use out of this product is as an additional monitor for control panels and tool palettes. If your laptop only has a VGA output and you need to connect to a DVI or HDMI (with adaptor) display, here is your answer.
Several companies have released products of this type, with Gefen being the most familiar, industry-grade name in the bunch. Currently, a company called Coolgear is running the lowest price.