Many thanks to SWLing Post contributor Perry Lusk, who writes:

Thanks to Dan Greenall for the article on SDR waterfalls. There is a lot of activity lately that I have found on the Kiwi SDR KF8KK located in Michigan.

So far, Stern Radio has the most creative examples:

As you can see, they broadcast in Motorola C-QUAM Stereo AM. The SDR will decode it by selecting QAM next to the AM mode button. It is quite the experience.

I have also attached an audio recording in stereo: