Did you know you can have your Mac read to you? Well it can. You can be looking at a website or a PDF or some other doc and have the system read it for you.
This is a great way to help you speed read or just to not fall asleep while studying a long document.
So how do you set this up? Go into the Apple menu then System Preferences. Then choose the Accessibility icon and select Speech. Here you can configure the options to enable Speech.
Then all you have to do is highlight the text and select Option+Esc and Voila, the computer is reading to you.