I contributed the Pseudodragon entry in the Baby Bestiary, vol. 2! (Print | 
PDF)
This was such a fun project to work on! Metal Weave Games posted asking for last-minute contributors after a couple of theirs backed out, and I jumped at the chance. I love pseudodragons, and had a lot of fun researching old monster manuals for “historical interpretations” and then imagining such creatures in a “pet/companion” capacity for adventurers.
The project also showed me a lot about how to really engage your contributors. Metal Weave had a “Baby Bestiary Contributors” hangout chat going at all times, and would regularly post adorable sketches and finished artwork from the book as they went. They also included a hard-copy of the book for contributors as part of the compensation package.
In all, it was a good project to work on, both because of the content, and because of the project management. I learned a lot about how I want to treat my own contributors from this project!