The wonderful “Wankle Rotary Engine!”
It’s fun to say, and, apart from the old “you need a new fuel pump” trick, has indirectly provided a college education for many a mechanic’s offspring.
“Nougat”
Where would we be without it?
think about that…
My two favorites:
INDOOR PLUMBING
and…
HOT WATER PLUMBING
Blowjobs, easily.
I think that also falls under “discovery”.
Actually, Onan didn’t invent anything. He just discovered what every male baby before him already knew, but he figured it was worth dying for. (Hmmm, maybe 'tis.) 
As for invention, the bamboo back-scratcher gets my vote. I have one in every room. I couldn’t get along without them. Aaaaaah! That feels almost as good as Onan’s discovery! 
To everyone who voted for beer: Nonsense, you’re just saying that because you’re drunk. (Like me.)
To all those who mentioned airconditioning: You horrible people! Airconditioning is one of those things, like antibiotics and “Pulp Fiction,” that were good ideas but have been turned to horrible purposes. I live in Memphis, Tennessee, and I don’t have airconditioning and I am glad of it.
To those who mentioned stuff their great-grandfathers invented: My great-grandfather invented fish ladders. That’s where, when you build a big dam, you also build a little stream around the dam so the fish can swim up it to spawn. The family lore goes like this: This ancestor of ours got the idea and got one built, and got whoever was the governor of Oregon (where they lived) at the time to come see it, and the governor said, “Gentlemen, I never would have believed it would work if I hadn’t seen it.” May not be true, but a good story.
And finally, my vote for greatest invention is the light bulb. Well, that’s a tie: light bulbs and GOVERNMENT. We can bitch all we want about our particular government, but life without it would be a misery. Maybe I should amend that to democracy…
My Votes:
(1) -cheese-flavored dog foods (“finally your dog is getting enough cheese”
(2) feminie hygeine spray
(3)“tidy-bowl” toilet bowl blue dye
All other inventions are nothing compared to these!
The Dictionary.
The Egyptians didn’t have the wheel and they build what are still the largest columned buildings that exist. (What ever those are.)
Batteries.
cold beer - warm beer is the reason Britain lost her empire.
my father also said that in WWII, it was a universally held believe that the greatest invention of all time was canned beer.
Well, out of all of the great inventions, let me cull a few at random.
Steel
Gunpowder
Systems of Mathematics
The Dynamo
The internal combustion engine
Aircraft
The Transistor
Plastic
Ranchoth
(No, that’s my sig, such as it is. I’m not THAT much of an egomaniac.)
I was under the impression that the Egyptians did have the wheel. They used chariots, didn’t they. What they really lacked was paved roads.
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The women’s Scratch and Sniff T-Shirt. I’ve only seen one of these so far. It was a t-shirt with a picture of a cartoon monkey holding out a banana, and across the top, it said in big letters “Banana,” and you scratch it, sniff it, and it smells like…banana. It’s the perfect excuse to fondle a strange girl’s breasts, stick your face in her bossom, and go “BBllbbbllbblllbbllbbb.”
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Fuck beer, I say whiskey.
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Simply because I’m an addict, the Crappy Movie.
Hmmm. Yeah. That Discovery and History Channel s–t keeps saying they built the pyramids and temples without wheels. Any historians on the SDMB?
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The game of basketball
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Microwave
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Rocking Chair
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Anesthesia
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Coke / Diet Coke
-
Compass
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Micromesh / Cotton Fabrics
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Frontline and Heartguard
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Summer Vacation
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Cinema / Popcorn
Refining/smelting metals
The transistor
Playboy Magazine
Music
This discussion was held before at http://boards.straightdope.com/sdmb/showthread.php?threadid=70804&highlight=steam+engine
It is still the steam engine.