A very simple Hello World application written in C# which runs on a ubuntu-based Docker image. (https://github.com/ghedin/docker-mono)
How to run:
$ docker pull fghedin/docker-mono-hello
$ docker run fghedin/docker-mono-hello
Hello World
==== Based on http://mikehadlow.blogspot.com.br/2014/04/a-docker-hello-world-with-mono.html