Interesting metaphor: shipping software is like flying commercial airlines from A to B. Haven't thought of this previously, but it totally makes sense. What's a web-based system then? I can think of a taxi ride: even if you miss one taxi, you can get the next one with no hassle. (If you screw up something on the web, you can just deploy an update.)
There are also different types of planes. MS Office is Boeing 747 -- having done great work for a long time and seeing occasional upgrades. Windows Vista is Airbus A380: both are humongous and made with great fanfare and are "something unseen previously" but serious delays in shipping.
I'd be tempted to call Skype a modern fighter like maybe F/A-18, since it moves with great speed and maneuverability. Or F-117 since it was under most other guys' radars for a long time. But both are wrong since it's not designed to carry weapons, shoot other guys down and kill. So maybe it's a Yak-54 or any other similar acrobatic aircraft, being small, acrobatic and able to make unexpected moves. Or Cessna 172, easy to learn and fly and popular all over the world.