Macros in Cloudformation is actually what powers the Serverless Application Model.
Now you can use them in your own templates, to add more advanced functionality. The possibilities are endless.
This will make it possible to write your own intrinsic like functions that do magic behind the scene.
You will find my different macro experiments in this repository. Enjoy!!
Ec2KeyPair - An macro that will create and rotate EC2 Key pairs.
CommonTags - An macro for adding common tags to all resources.