Haha, for me, it has to be Electricity, because without it, we wouldn't have all that list...
Though, it wasn't really an Invention persay, since it was already around in some form as Electrons, but just not captured.
Then the same could be said about the Phone. Without that, Internet wouldn't have even started off.
THING TO ADD:
You'll have to add the Vacume tube, which was used before the Transistor was made, which of course made the computers of today possible, and to stop filling up entire rooms