Deliberate Camera Movement
While many photographers work hard to remove any kind of camera shake or movement to prevent blurry pictures, sometimes camera movement can be used for artistic effect. For example, camera movement combined with an appropriate shutter speed can produce very dynamic effects that give a sense of movement much better than a still-frozen shot.
We are used to the concept of panning in movies. The camera moves to follow a person walking down a street, for example. However, this technique has not been used as much in still photography. In photography movement is relative. If a photographer follows a person running down a football field at the same rate the person is running, the photograph of that person will be sharp while the background may be blurred.
A camera can also be moved through an environment. You have probably seen videos of streams of lights rushing by as a person drives down the highway. You can accomplish this same effect in still photography by mounting a camera to the top of the dash of your car, setting the camera to a slow shutter speed (several seconds), and then driving down the road.