Shawn Blanc on the inbox zone-out cycle and how to refocus. The cycle he refers to are those points during the day when you find yourself flipping between email, Twitter, RSS, etc., just waiting for something new to come along.
A simple way to help avoid ever even getting into the zone-out cycle is to only ever check your email or twitter or RSS feeds when you’re actually able and willing to act on those inboxes. Which is, of course, much easier said than done.