Amazing, but...
I wonder if you could improve the point system for it. I found myself catching up to the gray text, and it wouldn't let me progress past the white. This should be fixed.
Perhaps error-free lines could reward the player with a slowed progression of the whitened text? There are a lot of ways you could make this great concept into a really fun game.
As mentioned above, varying difficulties would be a plus; once I'm halfway through the 3rd paragraph the speed is too much, and no amount of typing seems to prove useful.
Great game! 7 stars only, but if you tweak it here and there I'm sure it will be 10. Congrats on the front page, too ^_^