I've been thinking about some of the ways users can deanonymize themselves when posting on a forum.
Besides password re-use from non-anonymous accounts (which password managers deal with), writing style (Anonymouth is supposed to deal with that - openjdk support in progress), Re-using a non-anonymous username by mistake is a remaining problem.
I found a simple python username generator that has an optional GUI. It combines words from a pre-defined list:
https://github.com/korons/username-generator
License: GPL2
IMHO this is a simple tool really worth packaging for Whonix.