Originally Posted by ypocaramel
There's the n home screen button. Other people have talked about using the volume buttons for the other two keys and forgetting the Google search button entirely.
the other two buttons are actually software buttons. they only show up when you load a pdf from your sd card (possibly loading a pdf on any location may work, but i've only tried sd card).
with a pdf open you'll see the back and menu buttons to the right of the read it now button.
if you leave the pdf as your last read book when you press the read it now button in other programs, instead of opening the pdf again it just pops up the back and menu buttons. the is great for web browsing since you don't have to scroll all the way to the top to access the back, forward, refresh, etc. buttons.