It was only a couple of weeks ago that I learned about the keystroke combinations Ctrl+Backspace and Ctrl+Delete: in many Windows applications, these delete, respectively, the word before or after the cursor.
I was familiar with Backspace and Delete on their own, for deleting backwards and forwards, but somehow, in all my years of computing, never picked up Ctrl+Backspace or Ctrl+Delete for wordwise deletion. And now I'm both surprised how many programs support it (I presume most of them simply by inheriting the behaviour from standard Windows controls) and how useful this is.
(I do know Ctrl+Insert, which goes with Shift+Delete and Shift+Insert for Copy, Cut, and Paste, respectively, though modern convention is to use Ctrl+C/Ctrl+X/Ctrl+V, respectively. The older series is completed by Alt+Backspace for Undo, corresponding to Ctrl+Z in the newer one, though I don't think I ever use Alt+Backspace. I do use either series for cut/copy/paste, depending on all sorts of things. I suspect that I use Shift+Delete most often for Cut but Ctrl+C and Ctrl+V for Copy and Paste, perhaps because the combination with Delete for Cut is more evocative.)