Psychologists at the University of British Columbia have conducted a study on the cognitive effects of colors. They found that red helped subjects concentrate while blue led to greater creativity.
"Think about red, and what comes to mind: stop lights, stop signs, danger, ambulances…People want to avoid those things, and that's why they do better on detail-oriented tasks…Blue is the color of the sky, the ocean, safety…When their environment is safe, people are more explorative."
http://blog.wired.com/wiredscience/2009/02/coloreffects.html
From the Upcoming ueue, submitted by whitespace.