The C/AL (MS Dynamics NAV) coding guidelines have been posted here. They include design, internationalization, localizability, readability, design patterns, cookbook recipes and more.
The guidelines will evolve over time, but a PDF snapshot as of January 2015 can also be downloaded from here.
There is a new Dynamics NAV Design Patterns forum available on Mibuso.com. The forum is moderated by Mark Brummel. You may also find the Design Patterns Wiki and Design Patterns Videos interesting.
They have begun posting the NAV Tech Days 2015 presentations on Mibuso. I was not able to attend this year, but the presentations look interesting. There is lots of great information on NAV 2016. Go check them out!
They have begun posting the NAV Tech Days 2014 presentations on Mibuso. If you were not one of the lucky ones who were able to attend, I recommend watching these great presentations. Even if you were able to attend, I would even suggest watching them again!