One of the iPad’s handiest features is its keyboard-shortcut cheatsheet. Whenever you have a USB or Bluetooth keyboard attached to your iPad, just hold down the Command key and wait for a second. An overlay will pop up showing you all the keyboard shortcuts available for the current app.
Did you ever wish you could do the same with the Mac? After all, you always have a keyboard connected the Mac, so a cheatsheet overlay should be even more useful. Then you need CheatSheet, an app that does exactly that.