Clive Thompson has a good piece in Wired: Why Idling Mind Is Mother of Invention. He cites evidence that lots of important processing goes on in the brain when we daydream. This leads Clive to ask:

If he’s right, we ought to think about redesigning the way we work. Modern productivity software is made to minimize mental drift. We ruthlessly track our progress on each task, click off to-do lists, design our workdays with Google-Calendered five-minute-increment meetings. How about designing software that optimizes daydreaming?