I’ve just created a repository with several extensions I used in projects divided into several files that may be combined as necessary:
https://github.com/ErsatzMoco/ulisp-extensions
I did this to better keep track of my own extensions, but I’d also like to suggest there maybe should be a permanent category that lists all available extensions and their repositories.
That way uLisp might get even more accessible, showing all supported hardware in one place.