A colleague at Lab49 just informed me of the existence of Rapid Serial Visual Presentation/RSVP speed reading apps. They’re amazing. Basically, the words of your reading selection are displayed in place one after another. With this interface, 300 words per minute seems slow to me and I can easily read news articles at 600 wpm.
These apps are available on web and mobile. On the web I’m using spreeder which has a website and chrome extension. Just highlight web page text, right click and choose so spreed it. Using the spreeder bookmarklet may be the best choice here since it has keyboard control for increasing and decreasing the speed while reading. Using the Shortcut Manager extension, you can make a shortcut for the bookmarklet and just highlight and hotkey.