You all probably recognise this problem:
You have selected a large area of cells and want to make sure you have included everything you wanted to select. Of course you can do the tedious chore of pulling the scrollbar with your mouse to find the other corners of your selection. Or you might hit the tab key to move through the selected cells.
But there is a much simpler way which enables you to quickly step through the corners of the selection. Just hit control+. (control+period) repeatedly.