(To those noticing the BARQSX review below, the developer replied and set the record straight; all is well.)
Now, as to the product - it's awesome! I've used a similar tachistoscope program called Ace Reader for years. However, that program is both fairly expensive and much more involved than I've wanted. iReadFast is much more Maclike; simple, easy to use, very attractive, and works just as advertised. And since it's free, everyone can try out this great tool and improve their reading speed!
The only think I can think to add to this program in the future might be the ability to display multiple words at a time, since some speed reading techniques involve taking in whole phrases at a time instead of single words. But I am not certain whether this chunking technique can be used with tachistoscope presentation or whether the reader must choose his/her own chunk of words on which to focus.
Mille grazie per questo buonisimo regalo, signore Del Maschio!