Draftin is a great. I often use the Hemingway writing mode (no backspace or delete). I make the browser full screen, switch off the spell checker, and just write.
Great idea guys, this will benefit the visual impairment community greatly :). I had a similar idea several years ago but for the web. Where you could use a sighted person's eyes to navigate a webpage.
An alternative could be cloud based eye tracking testing services such as http://www.gazehub.com/ where you can get a lot info about how visitos navigate... and you dont need large volumes of traffic