It’s easy to underestimate boredom.
However, boredom and its synonyms can also become a crucial tool of creativity. When people are immersed in monotony, they automatically lapse into a very special form of brain activity: mind-wandering.
In recent years neuroscience has dramatically revised our views of mind-wandering. [P]eople who consistently engage in more mind-wandering score significantly higher on various measures of creativity.
From the ever-fascinating Jonah Lehrer's essay, The Importance of Mind-Wandering in Wired.