PubWriter supports Font Awesome 5 which allows you to pick from over 900 unique icons for your PubWriter site.
For more help, visit:
List of all icons available:
https://fontawesome.com/icons?m=free/
How to grab the code:
http://fontawesome.io/examples/
In case you need the cheatsheet.
Samples in use:
Here are some of the more popular ones:
You can spin 'em too!