I have blogged about how my productivity improved with a second monitor, but today I got the specific references to the research on the topic. Microsoft Research writes that two screens are 50% better than one, and the University of Utah has shown that users make up to 33% fewer mistakes with more than one monitor.
DisplayLink makes a USB-DVI adapter with software to power the USB interface for display purposes. This product greatly reduces the power consumption of a multi-port DVI card in the PC, and according to their research by as much as 80% less.
Here's the Interop movie of their demonstration. There's a beta driver for Mac OS X too!
