First thing that came to mind. I remember in school at least 10 years ago we used it because a teacher liked it. Most of us just used it as a Powerpoint alternative, but a few kids definitely harnessed the extra power available over a generic slideshow. I remember being really impressed at the creative presentations a few people made with it. Fun times.
I made a resume with Prezi that landed me a pretty great job, and then never used it again.
It was really great for that one use case: something the recipient could click through and continuously be surprised by the complexity of without having to know the tool. Click. Wow! It got bigger. Click. Woah! It got bigger and rotated!
