Coppied from an email I sent to some friends:
start here:
http://trevor.smith.name/EST/ then click the link at the top of that page to grab the app for doing it with your own texts ;)
ie here:
http://trevor.typepad.com/blog/2004/07/speed_read_your.html --
Thought: An interesting application of this, given the camera built into the new iMac (see apples site) would be to write an app that used the camera to make sure the reader was looking at the screen, and pause the display of the text when the reader looked away or closed their eyes. (FWIW, this isn't an original idea exactly, I think I read it in a Heinlein book, but I can't recall specifics atm.)
also, I'm gonna stick the text of this email up as a post on my livejournal.