Just off the top of my head:

-There was a big push to improve aviation. US bombers at the end of the war flew at altitudes Japanese fighters from the beginning of the war couldn't reach. The first jet engines were also developed during the war, though they didn't see much action.

-The nuclear bomb is the most visible development, and through the cold war it shaped the postwar global order. But in non-military terms the Manhattan project was still groundbreaking, paving the way for nuclear power and a major jump forward in science.

-Some medical technology, like blood plasma, was used in WWII for the first time and helped to save a great many soldiers.

-The British codebreakers at Bletchley park created the first large-scale digital programmable electronic computer. Unfortunately they were all sworn to secrecy for decades so it had limited impact at the time.

-Radar was widely used for the first time, and the devices fundamental to it would eventually lead to other inventions such as the microwave.

-The Germans created the V-2 rocket bomb to strike London. It was the first rocket of its type, and the experts responsible for its development would be recruited by both the US and the USSR. This directly lead to the space race. Without German rocket scientists, we wouldn't have gone to the moon.

-It's more fashion than technology, but the T-shirt was popularized after it was issued as an undershirt to US troops. Stationed in the warm south seas, some soldiers wouldn't wear anything over it.

-While Penicillin had been discovered several decades before, it wasn't until WWII that it was mass produced, only becoming available to the general public around the end of the war.

-Advances to weaponry and tactics should go without mentioning.

-There are many, many others I'm either neglecting to mention or forgetting at the moment. WWII advanced a lot of industries, and nuclear physics, computers, cryptography, and rocketry all have very solid roots in it.