Easily switch between cameras in scene.
Download the file "camera_manager.py" then open blender, go to user settings(Ctrl-Alt-U) and select "Install from file".
Find the file previously downloaded file and click "install".
In the 3D Viewport press T to open the tool shelf, than under the "tools" tap there should be a panel called "Camera Manager":
The dropdown allows you to choose the active camera from all the cameras in the current scene. Below the dropdown there is a text field where you can change the name of the active camera.