This is perhaps something not everyone will be interested in, but in Norwegian newspapers they often have articles where a static, fullscreen background image fades to a new one as you scroll down the page.
I liked this style so copied it using Pro, setting up sections with BG images and using opacity changes controlled by scroll effects and .x-effect-enter
and .x-effect-exit
.
This was a few years ago and it was a bit tricky to figure out, but I like the end result: