For me, it helps to read the quote out loud or at least mouth it as I type it. Of course all the other things you hear all the time help as well -- accuracy is the most important thing for speed in my opinion. Also, it makes a huge difference when you're not mashing on the keyboard. A lot of people seem to hit the keys way too hard.

Hey, I was wondering if you could give me some tips for improving more. I've reached 90 WPM, and I've perfected touch-typing, but I've hit a speed wall and can't improve anymore. What do you think?