I read through the list. Some good ones. I think it is interesting that many found it so difficult to stick to the 2000 year cut off. Is it really the case that all the big inventions happened so long ago? This is surely an important and profound statement, if correct.
I have two suggestions, both within the cut-off period. First, the electric light, born about 50 years before Joseph Swan put a patent on the incandescent lamp in 1878, and then Edison in 1879. Having lived in Africa, where one is often forced to read from fire light, electricity is a god send. Moreover, having invented the incandescent lamp, it didn't take too long to come up with the flashlight, another handy device for those of us working in dark jungles. My second suggestion for great inventions is the aspirin, invented, oddly enough in 1853 in France. Clearly, other medicines have been around, many of which serve comparable functions, but what a useful little pill. Among the Maasai in Kenya, headaches are treated with goat feces, a mud compact to the head. I prefer the aspirin personally.