The reference git-shell implementation provides "~/git-shell-commands" feature - executable files in the directory are available from within restricted shell. That can be used to provide various additional features, e.g. listing repositories, creating or destroying, accesible via shell.
The idea is to provide basic repository management via shell:
ssh firstname.lastname@example.org list|ls [<namespace>]- list own repositories, list repositories from within namespace that current user has access to ssh email@example.com create [--public] <repository> - create private, public repository ssh firstname.lastname@example.org destroy [--force] <repository> - destroy repository, by default ask user to type repository name, --force allows to skip check i.e. for non-interactive removal