Talk I gave at puppetconf2013 on using exported resources to dynamically configure your system. Using augeas and concat the examples build up a working dns implementation that is automatic. The system was simplified a lot for the talk but the principles of using exported resources to configure the system is powerful.
Puppet posted the video.
The slides are here: http://goo.gl/nR9rti
There are some video examples embedded in the video as well.
https://www.youtube.com/watch?v=sif_PJfLT3s and https://www.youtube.com/watch?v=RHGQQMFFReA