This product is now free, get it here: https://github.com/josephclaytonhansen/blender-addons

ShotDial allows you to switch between camera views quickly and easily with just one keypress. Press Ctrl+W to switch which camera view is active!

NEW: Press Alt+M to add a marker and bind the current camera to the current frame!

The Show View add-on that comes with Blender is incredible, but it lacks a huge feature-the ability to switch between camera previews from your keyboard. ShotDial lets you switch which camera is previewed in the viewport with just Crtl+W. Works with 1 or a thousand cameras-you'll loop through back to the first camera when you reach your last. 

Press Crtl+W to move forward through camera views, and Crtl+Shift+W to move backward.

New in version 1.2: Press Alt+M to add a marker and bind the current camera to the current frame

New in version 1.2.1: Switch cameras / add bound markers directly from the timeline header: 

This is designed to work with a custom Arduino controller using a rotary encoder, feel free to email me at j@jhansen.art if you'd like the .ino code for that