iOS: If you read a lot, it's can be helpful to learn speed-reading. One good way to learn is to go through your current backlog of things you want to read. If you have a lot of articles saved in Pocket, Instapaper or Readability, you're in luck, because Outread will help you get through them and learn speed-reading in the process.
The app is similar to Syllable as it uses the same technique: reducing subvocalisation, which means reading at a pace faster than your mind can say the words. There's a sweet spot beyond that where you are able to comprehend everything you read without saying the words in your mind — and Outread's focus is to get you there.
Hook it up with your Pocket, Instapaper or Readability and it will import those reading lists. You can also add a bookmarklet to Safari to save articles to Outread directly, and add links or custom text to Outread.
It starts by highlighting words in the paragraph, slowly increasing speed as you go along. There's an easy-to-access preferences tab where you can fiddle around with the speed of reading as well as the range of words being highlighted. Go deeper into the settings and you get some more customisation options, such as picking the font and switching between light and dark themes.
The only things lacking in Outread at the moment is an iPad app and support for ebooks. It's a little baffling that it doesn't support the iOS device that most people read on, or the things they read on it. But even without that, it's a pretty cool app to learn speed-reading while getting through those articles you meant to read some day.