What does your room look like?
jseliger: Mine looks like <a href="http://jseliger.wordpress.com/2008/06/21/new-workspace/">this</a>. The important thing is the cleanliness of the desk: just a computer and a backup hard drive I can't see when I'm typing. The books were ones I was using when the picture was taken.Mostly, the desk doesn't have a lot of visual distractions. It's there chiefly for thinking, and I think a clean space helps thinking. The only major features are books, and those 1) put me in the thinking mood and 2) are occasionally consulted. Other posters have commented on the value of a plaything; I often have a squeeze ball to relieve stress and keep my arm from cramping, as well as a fountain pen, but otherwise it's clear.