Today I accidentally learned that ctrl-a and ctrl-x increment or decrement the number under the cursor. That's not terribly useful unless you're dealing with a lot of numbers, but if you are, it will save a lot of keystrokes.
One set of movement keys the article didn't mention but which I use all the time are H M and L (shift-h, etc.) They jump to top (high), middle, and bottom (low) of the editor window, respectively.
The same goes for ci' or ci".
a = 'foo' // imagine the cursor on the letter a
Executing ci'bar will change foo to bar.
To the point that I have used c-x c-a as a stupid shortcut to jump to the next number on a line. I'm sure there's a better way to do this, but it's fast so...
I personally added a "number" text object, so that I can treat numbers just like "words", and also created a "jump to number" shortcut.
Make no mistake: that is terribly useful, even if you're not dealing with a lot of numbers. You just found out about it so maybe you haven't realized it just yet. The mere fact that it accepts a count (i.e. 10<C-X>) and it's repeatable with the dot operator makes it a killer feature.
To make the shortcut smarter and able to deal with dates and times I recommend vim-speeddating by Tim Pope: