I have updated the PR with a FAQ that mentions all implementations mentioned here, except Cython and Stackless Python.

I added RapydScript as it's used by VPython for Web visualization, in the category of client-side scripting pythonesque languages/implementations.

I didn't add Cython because it's not clear to me if it's useful for creating extension modules in a pythonesque language, or if it's also useful by it's own.

I didn't add Stackless Python because it doesn't fit with the "problem domain specific" category I've chosen for the FAQ.

I'm pretty sure this will need a few iterations, but at least we have an starting point :)