I'm trying to do that for a small community site but I find the documentation a bit lacking. I know I have to create a directory somewhere and write a web.config in XML but I'm still figuring out the rest. I may end up copying someones Github project and tearing it apart to see how things work in practice, or perhaps my RTFM skills are somewhat lacking lately. But if you'd ask me I'd say the widespread presumption all developers are running Visual Studio.NET with Nuget is part of why you haven't seen those success stories.

On the bright side, I've heard good things coming out of ServiceStack. Apparently it shines in the backend web service department and works well with Mono. It's based on ASP.NET and since the requirements for my little project are fairly minimal, I think it's a bit overkill there. But it's still worth checking out for more demanding projects, IMHO.

I've created a Mono buildpack for Heroku that runs MVC amongst many other things: https://github.com/friism/heroku-buildpack-mono