I also appreciate using `git whoami` to check the current identity settings:

    $ git whoami 
    GIT_COMMITTER_IDENT=Mel Smith <mel@example.org>
    GIT_AUTHOR_IDENT=Mel Smith <mel@example.org>

`whoami` can be implemented via a simple alias:

    git config --global alias.whoami = "! git var -l | grep '^GIT_.*_IDENT'"