You can download a trial version to see if you like it from Mindola Software at http://www.mindola.com/snc/index.html There are also screenshots and testimonials from writers who use the software and have made suggestions as to what could be included to improve functionality in later versions.
I don't know what I ever did without it!
Momentum Writer is a (free) software that comes in very handy during writing marathons like GothNoWriMo and NaNoWriMo. It has been developed by Black Obelisk Software, the creators of Liquid Story Binder.
Momentum Writer is the ultimate tool for distraction-free writing. Like a mechanical typewriter, users are prevented from editing previously written text. There are no specific formatting options, no scrolling, deleting, or revisions. Momentum Writer doesn’t even allow you to use the backspace key. Momentum Writer forces you to write, to move forward, to add new words. It halts the temptation to linger, revise, and correct.
You can download Momentum Writer at http://www.blackobelisksoftware.com/momentumwriter/index.html