I typically draft stories in
Scrivener, but there's an awesome website that has changed my writing habits. It's called
Ilys, and you have to check it out to really see how it works.
The basics: you enter the # of words you want to write. When you click "go," you're taken to a black screen with a large box in the middle. Each letter you type flashes in the box and then is replaced by the next letter you type. A word count meter is at the top of the box. Below the box, you can click an "eye" to see what you've written so far--but you can't edit it until you've hit your word-count goal.
It forces you to write without editing, and to concentrate on telling your story rather than getting the words right.*
Try it out! You might be surprised at how much it changes the way you write.
*Once I finish my first draft, I go back and paste it into Scrivener, where I can edit and revise.