Write or Die
Write or Die operates by the principle that one will type more quickly and without pause if threatened. Are you going to slacken your pace with a gun to your temple? In this case, the threat is much less mortal (at least until the Electric Shock Mode is implemented). In Gentle Mode, the site will sweetly pester with a pop-up that one ought to be writing. In Normal Mode, one will hear a grating sound (out-of-tune violin, Bananaphone) if one stops typing for more than a moment, though warning is given through a gradual reddening of the background. When one again touches the keys, the red vanishes to white and the deterrent ceases in an instant, whether or not one actually does anything more than click left and right. The worst mode is Kamikaze, where the website will delete words if one stops typing, which seems counterintuitive to the goal of getting the words out. Threaten me all you like, but be prepared to lose a finger joint if you try to touch my delete key when I am on a roll and take a breath. Writers have enough issues with editors without having a website arbitrarily fighting them for a word count.
I would love to say that this does not work for me, that I can work simply for the rewards of having finished, but I really don't care to see the screen turn red. It is more competing against myself in a time trial than avoiding auditory punishment, but it is effective to screen out distractions. There seems to be no website based reward for finishing one's word count in time, but there is a congratulatory sound if one shells out $10 for the desktop version. And, really, isn't that worth your Hamilton?
The desktop version has various other features for increasing word count at the expense of writing intelligibly (in that I have witnessed people using Write Or Die typing song lyrics or gibberish to keep the site from screeching at them), such as disabling the backspace and making it so one cannot save one's work until the goal word count is reached. Cheating the system is easy but (unless one is in the Challenge Mode that is only available with the desktop version), one is only cheating oneself. Then again, we are talking about writers here and we can't be trusted not to sprinkle catnip on the keyboard, position a cat before it, and wander off to the pub for a bit.
It is beyond important to set reasonable goals for oneself if one is a writer, as I know many who give up when they discover their Harry Potter fan fiction is not going to earn them Rowling's royalties. Write or Die puts the goal to a much more attainable level of a few thousand words for fear of punishment, which might be help enough for most writers.