I wrote an application for sharing markdown text, which you can view only at http://markdownshare.com/
If you wanted to install it you'd need to fetch all the dependencies, configure them, setup a webserver, etc.
Or you could clone the repository then run:
docker -t markdown/share build
And launch it as a container: docker -d -p 8080:80 markdown/share
That's neat, and shows how you can create/install applications and run them in an isolated fashion. e.g. Graphite, Wordpress, etc.