Need students to practice typing for a certain amount of time? Want to improve your own writing and thought process? Want a challenge? The Most Dangerous Writing App site allows you to set a time frame to start and finish your writing. If you complete the time you are rewarded with a text file of your work. If you pause (for around 5 seconds as far as I can tell) all of your work is lost.
Looks like you can set the timer for 3, 5, 10, 20, 30, or 60 minutes or 75, 150, 250, 500, 1667 words. In regular mode you see your text as you type. However, there is also a hardcore mode. This blurs your text after it is typed. All you will see is a giant letter of the key you just pressed.
I tried the three minutes and it was hard to put a congruent thought for that long with my mind thinking I need to type something so I don't lose all of my work. I could see this as keyboarding a challenge where students are transcribing from another text. But I could also see this for the unmotivated writer who needs to work under a deadline.
Check out the site and give it a try.