You don’t need to use a screen reader to navigate a page with the keyboard. In the end we use the keyboard to trigger the commands within the screen reader. Sometimes the average Joe uses the keyboard, perhaps because he has to fill out a form and jumps from input field to input field with the Tab key. Or maybe it’s because his mouse is broken - in which case it would be so wonderful to have the option to navigate with the keyboard. Some pages embrace this by providing a list of shortcuts to trigger actions on their page. Twitter for instance has a great list of shortcuts that make the keyboard more effective. To see the list, simply hit Shift+? and it will open in a lightbox (you have to be logged in).
Most of Twitter's functionality can be done by using the keyboard. Obviously this needs a little bit of Javascript.
