If you are looking for some good startup templates for cloud formation, I found this repository from acloud.guru website a good starting place.
The templates provided gives a startup template on how to spin an EC2 instance. Of course there have to be more building blocks to it. But to kickstart for a demo or a presentation on how to use cloud formation, start with the first template, but to see a snake definition. Here is a greater addition.
Sathish Jayapal 