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the Grand Arcanum (various alchemical processes intended to produce the Philosopher's stone) - But I dare say chemistry is huge.
The Inca "knots tied in a rope" document format. - But documents in written languages are pretty common.
Ancient Egyptian stone drill bits. - But drill bits can be found here and there.
Greek Fire (though arguably Napalm is a modern equivalent) - Yes, Napalm and, well, bombs.
The ancient Babylonian legal code (Hamorabi I think) - But law codes and rule of law is rather abundant.
Vacume tubes - I think this one is beaten to death by other comments.
Any of a number of calendars from civilizations that didn't make it to the 20th century. - Yeah, but we didn't stop using calendars.
Aristotle/Arcamedies model of the Universe - Again, models of the universe do show up occasionally.
The 4 Humors - Borderline. There are new biological models that we use.
Inventions are not always tools. Tools accomplish a task. To extrapolate, the AMC Gremlin and the Ford Pinto are no longer manufactured, but that by no means indicates that we stopped using automobiles.