In emacs, when you press Ctrl-L, by default it runs recenter-top-bottom. This scrolls the document ("buffer") so the line the cursor is currently on is centered in the screen. If you press it again, it scrolls so the cursor is at the very top of the screen, and again puts the cursor at the very bottom. I've always been mildly irritated by this: the middle of the screen is lower than I want for the initial state; I generally want more context below the cursor than above. Additionally, scrolling to the top or bottom is nearly useless because I almost always want at least a little bit of context on both sides of the cursor.