When you hit your daily word-goal, stop. Stop even if you’re in the middle of a sentence. Especially if you’re in the middle of a sentence. That way, when you sit down at the keyboard the next day, your first five or ten words are already ordained, so that you get a little push before you begin your work. Knitters leave a bit of yarn sticking out of the day’s knitting so they know where to pick up the next day — they call it the “hint.” Potters leave a rough edge on the wet clay before they wrap it in plastic for the night — it’s hard to build on a smooth edge.
Also checkout this Distraction free writing tools round-up from Pink on Brown.
Me, I’ve been embracing chaos lately, accepting that I won’t sit down for 20 minutes of uninterrupted writing time and just doing 5 minutes here and there. Leaving Google Docs tabs open to write in when I have the urge (or sometimes when I don’t have the urge). Switching between writing and Twittering and Google Reader and washing the dishes. It’s been working for me lately but it may not be a sustainable way to get writing done.