Pervitin was an early form of methamphetamine, in large use by the Nazi military. Kept soldiers awake and alert and minimized appetite to stretch rations. Research around it and similar things helped further addiction and psychological distress.

Elektroboot was the first electric submarine able to stay submerged for large lengths of time without needing to vent things like diesel exhaust. Even being able to charge while submerged.

The Intramedullary Rod, an essential part of modern orthopedic surgery to heal broken bones.

The Horton Ho 229 was an early attempt at stealth and flying wing aircraft. While never fully produced, the development led to further research after resulting in modern stealth aircraft and overall aircraft efficiency, and by extension detection and tracking.

The Enigma Machine was a marvel of cryptographic security. Pretty sure this stands on its own.

Messerschmitt Me 262 was the first mass produced fighter jet. Much of even modern jet propulsion technology stemmed from this research.

3D Films were used to enhance their propaganda well before Hollywood considered it.

The Z4 Computer was one of the earliest commercial digital computers.

Of course the V2 rocket. And by extension every Project Paperclip scientist brought back to the US to develop space technology at NASA, up to and including the Saturn V rocket and Apollo missions.

The jerrycan, for fuel transport. Literally named after the British slang for German soldiers. So useful the Allies adopted it during the war.

Chloroquine, an anti-Malaria drug developed by the Nazis, initially toxic but further refined after the war.

Night vision technology also had massive developments made by their military scientists.