While working on a file opened using vim I often want to see the line where the cursor is at in the center or at the top (and sometime at the bottom) by scrolling up or down — and I often forget how to do that without using j, k or other cursor movement commands. Here’s how to do it:
z.[z followed by a dot (.)] — to put the line with the cursor at the center,
zt— to put the line with the cursor at the top
zb— to put the line with the cursor at the bottom of the screen.
NOTE: A somewhat related trick is to move your cursor to the top, middle or bottom of the screen without scrolling the page using H (i.e., shift+h), M and L, respectively.