zplug is a plugin manager for zsh shell.

Homepage: https://github.com/zplug/zplug
Is it Open Source? Yes
How many users do you anticipate will use this software? People who uses zsh regularly. So I would say a lot ...
Link to source tarball/zip file: https://github.com/zplug/zplug/archive/2.4.2.tar.gz
Why should this be included in the repository? It is very useful for zsh users and I am not aware of such software in the repo right now.