Jazzband is community of Python maintainers (Github organisation) that provide a common repository for projects and which allow the members write access to all the projects in the community.
Maintainers can shift their repositories to the organisation to provide a more robust ownership and maintenance structure. I'm surprised that I haven't seen this kind of collectivism for projects before as it seems it offers a path for solo maintainers to exit their projects responsibly.
2026 Update #
In March 2026 Jazzband announced it is shutting down. The "Slopocalypse" of AI-generated submissions was the precipitating event but there were wider problems including the general issue of unpaid labour in open source.
A number of projects have migrated to Django Commons.