There are a few companies using it in production (and I use it for my work as the author of it), I just haven't bothered to ask for permissions etc. I discussed with one of the ember core team about replacing ember-cli's http-mock/fixtures with fortune, it seems doable by reusing ember data models in the backend. since they both support JSON API standard, the interaction should be frictionless.

I've used it to prototype APIs during development, like this one: http://fort.herokuapp.com/api

The code for that one lives here: https://github.com/unindented/fortune-example