Shift+0 (zero) hides all the "____ started following you" posts
Shift+1 puts you in a cleaner mode where your browser seems to go into the "mobile" mode that I observed on my iPhone where you have three different screens:
your friends list
a big post window
On the iPhone you swipe between the screens. On a desktop you use the arrow keys.
Using the right arrow key in your main view hides your friends list and makes your feed full-screen.
Using Shift+5 creates a "grid" view that lets you see more of your feed. (Do this after pressing the right arrow key and you get a nice big screen of posts.)