Most of us don’t need more than one camera but most of us own more than one camera. I personally own film, instant, and digital cameras (several of each). Why? Because each provides me with a different look or facilitates taking a particular type of image.
My Nikon D800 makes it easy to produce very large prints while my Fujifilm XE-1 makes it easier to take photographs on the street because it is much lighter and smaller than the D800. I also have a small but wonderful collection of plastic film cameras, which are nice for two reasons: (1) you never know what will come out of the camera (because (a) the cameras are just not precise equipment and (b) the film must get developed first) and (2) you can take a break from worrying about complicated menus and settings. And why the instant cameras? They are just fun!
So, what kind of cameras do you use?