I miss Classic Mac OS extensions which added whimsical things like this.

As I remember there were a few cursor trail extensions, as well as an extension that added physics to dragged icons (you could even throw them!), an extension that turned all on-screen text upside-down, etc. Not the least bit useful but fun.

The Classic Mac OS extension model was a security and stability disaster but it was unparalleled in terms of how it let third party devs tweak the OS. Even modern Linux desktops can't compare.