I used baseimage-docker for a while but wasn't satisfied with the image size (around 300mb with nodejs installed), so I switched to debian as the base and removed stuff I didn't need such as syslog and openssh. That alone brought it down to 140mb.

However seeing as other people have managed to distribute their applications in images as small as 7mb (e.g. progrium/logspout), I decided to create one based on busybox with s6 as the process supervisor, with help from this article [1]. I'm now pretty happy with my 33mb nodejs environment :)

[1]: http://blog.tutum.co/2014/12/02/docker-and-s6-my-new-favorit...