Stumbled across this demo from 1968 and thought it was pretty cool. It's been dubbed "The Mother of all Demos" because Doug Engelbart goes on stage and demonstrates the mouse and the internet probably 20 years before they'd become mainstream technology.
I love how he mentions at the end that the ARPAnet will be coming online next year.
https://www.youtube.com/watch?v=B6rKUf9DWRI