Overall I've been impressed by @digitalocean's #Hacktoberfest to encourage people to contribute to open source.
It doesn't have any perverse incentives (you can 'cheat' with PRs on your own projects) but it celebrates developers who collaborate.
miniblog.
Related Posts
Changing a project's hosting to GitLab is a major undertaking. When KDE and GHC migrated, they had a tracking issue to list all the painpoints they had!
https://gitlab.com/gitlab-org/gitlab-ce/issues/53206
https://gitlab.com/gitlab-org/gitlab-ce/issues/55039
A great way to collaborate and for the GL maintainers to see what users need.