Nobody likes arriving at an empty coffee pot, especially computer scientists at Cambridge University. That's why, back in 1991, a team of them invented the world's first webcam to keep an eye on coffee levels from their desks.
Rigged up in the corridor within the old Computer Laboratory of the University of Cambridge, the camera stood next to a filter coffee machine. When switched on, the camera provided a 129×129 pixel greyscale image of the coffee pot at 1fps.
Modest, sure, but enough. Students and academics in the building could then keep one eye on the coffee level, by opening up the xcoffee stream on their desktop, to ensure they never had a wasted journey. (Incidentally, it's unclear who ever actually made the coffee, but let's not spoil a perfect story.)
Amusingly, if you count this as the invention of the webcam, it actually pre-dates the invention of the web by a couple of years. Needless to say though, that as soon as the web went live the feed was up there — where it remained until August 2001. Visit the site now, and you'll just find the final picture the camera acquired.