Perhaps not the Internet, but rather the technology it depends on: the computer. Just as guns were the great equalizer in violence (David could kill Goliath on a regular basis, and without any particular guile) the computer (and the Internet) are the great equalizer in knowledge and communications: If I have a computer connected to the Internet, I can store, process, and transmit as much information as I damn well please (in the words of Jimmy Wales, hard disks are cheap). In addition, computers allow for the extensive automation that makes so much of the way things work today possible. Without computers, factories would be less efficient, accounting would be far more difficult, and all manner of things we use every day (cars, microwaves, televisions, digital watches) would be either impossible, more difficult to use, or more difficult to repair. Computers are positively everywhere, and the world just wouldn't be the same without them.
The various forms of engine are all very important, too, but which one is most revolutionary? The steam engine, for starting it all? Or the internal combustion engine, for revolutionizing transportation (you can go ANYWHERE with a car!). Or the electric motor, for making other things possible?