Now there are machines, sensors, even cameras all round the world which can be accessed over the Net. Some of the most popular are those issuing weather reports and/or pictures, including a weather camera set up at the most northerly university in the world (in Norway). Others serve purposes both more and less useful. One robotic arm, situated at the University of Southern California, allowed remote users to interact with a (simulated) archaelogical dig, and add their theories about the items partially revealed; other interfaces allow you to monitor the progress of an ant farm, remotely control a model railway, check the contents of someone's refrigerator, and talk to a cat. (Unfortunately the cat has not yet learned to talk back.)
Many of the machines on the Net at present are maintained by hobbyists or students, just for fun. However, some of the more serious links show the shape of things to come; Olivetti, in Cambridge (UK), have a map which shows the locations of all their staff as given by their "active" badges, and the inventors of the robotic arm mentioned above have now developed the Tele-Garden, where users from all over the world can plant seeds, water the garden and monitor the progress of their seedlings. It may not sound revolutionary, but the techniques being developed could be used to perform operations remotely, or to move items in space or in other places inaccessible to humans.
Carnegie Mellon drinks machine:
http://porsche.botz.cs.cmu.edu:8001/htbin/coke2 [Possibly defunct.]
Online model railway: