Thank you for your good idea, and your enthusiasm. And I thank Guido, for suggesting a good contribution this list can make.

Here's some comments on the state of the art. In addition to

there's also

and

I expect that these three modules have some overlap in purpose and design (but probably not in code).

And if you're brave, there's also

and

Time to declare a special interest. I'm a long-time user and great fan of TeX / LaTeX. And some nice way of pretty-printing Python objects using TeX notation could be useful.

And also related is Geoffrey French's Larch environment for editing Python, which has a pretty-printing component.

with best wishes

Jonathan