Heroku is the main reason why we moved from PHP to Ruby/RoR. My first encounter with RoR made me feel managing a Ruby server was a pain and resources never enough, but Heroku made me fall in love again. Now we have at least 10 apps with them.
Free apps get killed every 24 hours and wont start up again until they get a hit (http://www.mail-archive.com/heroku@googlegroups.com/msg04562...). Possibly there are some paid apps that aren't getting used, but why would you pay every month for an app no one uses?
Probably > 95% of them are free apps with hardly any traffic.
But this is part of the beauty of Heroku. If you hack something together instead just storing it with "git push origin" you can do "git push heroku" and actually demo it to the world for free.
I like to think of Heroku's 100,000 apps as public demos of a lot of GitHub repositories.
Interesting, I totally thought they would have hit this a while ago. For some reason I assumed they might have hit a magnitude higher. But I guess I totally misunderstood their popularity. Whoo echo chamber.
Including mine. Love the service. It's sort of what I imagined hosting could be like but didn't think was possible. Anybody ever notice how cool the site design looks when you're working in the dark, late at night?