Hehe, CD's to me were more important in the 20th century, I dunno why tbh, but hard drives never really "changed" the way we use and share data. They have always seemed pretty boring, but I do agree, where the hell would be without them haha!
I think whilst hard drives have remained quite static and boring, CD's, in one form or another, progressed to change our lives so much in the 80's and 90's. Hard Drives really became exceptional in the very latter 90's, when they finally started reaching decent capacities and breaking technological barriers.
GigE's were mega for the 20th century too, they really made the internet "flow" like it should do, and opened up the future of high bandwidth internet leading to the 10GigE and 100GigE ports.