It was 40 years ago today that Douglas Engelbart gave a demonstration that introduced the public to an impressive list of technologies which would in the following years become established in the mainstream. On the 9th of December, 1968, he demonstrated:
hypertext (i.e. text with links that can be followed — a precursor to the Web);
It also demonstrates copy and paste, which although not completely new at the time, was still not especially common. A video of the demonstration can be seen on Google Video.