Cameras you can control
Very often, you will find cameras that you can control - you can pan from left to right, up and down, zoom in and out and change camera angles. Sometimes people have professional installers who remember to password protect the controls, very often, they do not. Sometimes, cameras are left open for the public to use and control at will. Sometimes you can find a popular camera and someone else is controlling it.
Every once in a while you might find one that is being used by security guards - you can really freak them out when you begin controlling their camera if it is not supposed to be publicly accessible.
Different types of controls
As you get used to the various webcams and after you have experimented a bit with the different search strings, you will find that there are a number of different controllers for cams depending upon the model.
You can try different search strings on your own in Google or any other search engine to find other cameras by coming up with your own variations of these strings.