The Internet. A huge distraction. You're writing happily away when suddenly you wonder whether your steampunk heroine ran into Einstein during her trip to Germany and, if so, was he young enough to date her. Thirty seconds later Wikipedia tells you yes … but thirty minutes later you mysteriously find yourself still researching the priority of relativity controversy.
So: the Internet goes off when I'm writing now, and I collect questions in a text file while I work for later research. So far, this plan is working well.
Sent from my gPhone.