This is probably my favorite, and the most useful of the in camera editing functions, the lens shift. Just like a shift lens, it allows you to change the perspective. The chief use is to make buildings that normally look like they are leaving over, to become straight again. As you can see from the shot below, it also crops the photo in order to achieve what you need.
Here's my example of the famous Jen's Hotel in Mount Gambier.
|Edited with Shift function|