More broadly I’m a big fan of format-bending issues that just don’t have the same effect in digital. I think it’s something about taking advantage of the nature of comics as a tangible physical object.
That recent Dan Slott Silver Surfer issue with a mobius strip is a good example. So is the Snyder/Capullo Batman issue that twists everything upside down. And the Promethea folded issue (and the one that was originally designed as a single giant long horizontal panel). Stuff like that.