It took way more time to find a simple widget that would allow for a rotating image in my sidebar. I wanted to use images already in my media library, and I didn't want more options than a modern fighter jet. I found it here. I only took off one star for media library integration. Once it's possible to display existing captions (for images sourced from the media library) rather than requiring a second caption to be set, it'll be five stars. Very happy.