Speedreading books.

[SpriggsySpriggs]

I wouldn't call it a dud. It is doing the exact same thing as Spritz (google.com), which is very popular for speedreading. I can't remember for what purpose, but the extension would also highlight one of the letters in red. I'm not sure if that was to force your eyes to the middle of the word or not. It's been years since I've used the extension.