difficult question…
motors (electric, diesel, etc)
clocks
lathe
pump
machines that form plastics
(computers, refrigerators, already mentioned)
my favorite… I would say “motorcycle”
I have no idea if it’s true or not but I once heard that the automatic transmission is the most complex machine ever built by man that doesn’t require the use of electricity to function.
I kinda like my bottle opener.
They used to be controlled entirely through mechanical means, with speed and load being sensed by centrifugal and vacuum devices. These days, computers are running the show, so late-model transmissions are dependent on electricity. Sorry.
Wheel and axle.
It’s a toss up between the Veg-O-Matic and the Pocket Fisherman.
Claude Shannon’s Ultimate Machine. The sum of all human toil and labor, minus the overhead.
I think it’s the Fender Telecaster guitar.
Those electric baby swings are pretty awesome.
Even more apt if you couple two together.
Add even more, and they’re beginning to seem really productive while still accomplishing, beautifully, bugger all. Add a modicum of intelligence—enough to care about flipping the next lever, to come up with reasons for it and rationalizations, but not enough to see what happens in the long run—and well, we’ve finally created our own replacement.
Enthusiastically seconded. But yes, alas, all the Blackbirds are retired: Lockheed SR-71 Blackbird - Wikipedia
A nuclear-powered fast attack submarine is a pretty amazing machine.
Likewise the Mars rovers.
Old joke:
Three engineers are arguing about the greatest technology ever. One says, “Nuclear reactors. You get vast power by splitting atoms! How cool is that?” The second says, “No, the Saturn V rocket. We sent men to the Moon with it!” The third shakes his head and says, “Neither of you know what you’re talking about. It’s the thermos bottle.”
“The thermos bottle?” the other two scoff. “All that does is keep hot things hot and cold things cold.”
“Ah,” says the third, “but how does it know?”
Saturn V rocket was the very first thing that popped into my mind. Next was the multi-protocol router. 
Pipe organ. Thousands of pipes and moving parts in an assembly of phenomenal complexity that can produce a staggeringly wide range of musical expression and inspire emotion to an extent unmatched by anything short of the voice of God Himself.
My wife read a mystery once, set in a small New England parish church which had a quirky old pipe organ. The organ maker included a DIV INSP stop which wasn’t connected to anything and did nothing - but the organist could pull it out when he or she really needed Divine Inspiration.
Good call, and i like the words you used… nice work.
I’ll throw another one out there… the coal-fired power plant. I’ve got an affinity for these, too, as their operation pays the bulk of my mortgage each month.
And to try and romanticize it as **Malacandra **did;
Hundreds of miles of ducts and wire, along with metric tonnes of coal coupled with the precise ratio of oxygen, all working in harmony to produce the fires of hell that are harnessed to boil earth’s life blood into a steamy workhorse used to turn the dynamos that power a civilization.
Counting modern complex machines, I’m sure refrigeration comes in very high on the list. Refrigeration and air conditioning have made vast swaths of the world pleasantly habitable.
The flush toilet
As far as revolutionizing an old technology and how people use it: the digital video recorder (DVR).
DVR’s completely changed how the majority of people watch television.
Oooohhh!
There is nothing cooler than the Turbo Encabulator.