From Wikimedia Commons: Picture of the Pitch Drop Experiment from University of Queensland featuring the current (2007) custodian, John Mainstone (picture taken in 1990), two years into the life of the 8th drop.
On what is quite likely the most boring webcam ever, you can stare in rapt dumb awe as a drop of Australian pitch (a petroleum product used in waterproofing, among other things) very, very, very slowly drips out of a funnel. How slowly? Well, only eight drops of pitch have fallen since the experiment began in 1927. However, according to this table, the 8th drop fell on November 28, 2000 (12.3 years after the previous drop in 1988), so we're due for another drop any time in the next, oh, year or so. Or not. You see, the pitch drops are quite variable because the experiment is subject to changing room temperatures, and the installation of air conditioning in 1988 in the experiment's home building has really slowed things down.
This pitch funnel currently holds the Guinness World Record for the longest continuously-running experiment. There are two other notable experiments that almost make the grade -- the 1840 Oxford Electric Bell and 1864 Beverly Clock -- they haven't been running continuously, but nearly so. Better luck next time, Nineteenth Century scientists!
From The University of Queensland's page on the experiment:
The first Professor of Physics at the University of Queensland, Professor Thomas Parnell, began an experiment in 1927 to illustrate that everyday materials can exhibit quite surprising properties. The experiment demonstrates the fluidity and high viscosity of pitch, a derivative of tar once used for waterproofing boats. At room temperature pitch feels solid - even brittle - and can easily be shattered with a blow from a hammer. It's quite amazing then, to see that pitch at room temperature is actually fluid!
In 1927 Professor Parnell heated a sample of pitch and poured it into a glass funnel with a sealed stem. Three years were allowed for the pitch to settle, and in 1930 the sealed stem was cut. From that date on the pitch has slowly dripped out of the funnel - so slowly that now, 80 years later, the ninth drop is only just forming.
If that isn't exciting enough for you, go watch grass grow in real time (warning: plays sound). (Update, 10:30am Pacific: Mr. Grass has added red lawn chairs to the lawn; things are heating up!)