I'll throw red dot style sighting systems out there, or more specifically the proliferation of sighting units like these since the War on Terror began.
The advantages that sights like the aimpoint bring to the table are pretty amazing: compatibility with night vision, speed of engagement, low light capability, both eyes open shooting.... On more than one occasion sights like these (as well as some similar illuminated magnifying optics to a lesser extent) truly made me wonder how we soldiered without these things, specifically in the arena of low light engagement.