Doug Engelbart 1968 Demo
A bit of computer history I'd run across some time ago, but forgotten the link.
First, this is interesting as history - the bare beginnings in the 1960's of technologies that only became widely used in the 1990's. No point in elaborating this oft-visited topic.
Second, this is interesting as illuminating a path not taken - an alternate future - in technology. Note the use a shared computer with video piped to the desktop. This is a pretty clever notion, and is potentially more cost-effective that legions of desktop computers.
There was a thread on USENET a long time back about the merits of shared versus desktop machines. The upshot was that in theory got you more bang for the buck with shared machines, but in practice shared systems are almost always mismanaged. With a shared system there is always the temptation for management to delay upgrades, so shared systems tended to become under-configured, and performance would degrade with time. With desktop machines - once acquired - you had a fixed resource over which you had complete control.