OpenDKIM key generation
When I was setting up DKIM/DMARC on my domains I got tired of the manual process of generating DKIM keys, managing the DNS records and updating the OpenDKIM package on the mail server to use the new keys every month. The result was Python software to simplify the key generation and DNS update process plus a pair of shell scripts that can be put into cron to automate the monthly update process. Results including errors are reported via email.
The package is available on Github (or as a zipfile of the latest release) rather than through PyPI or pip because it's more or less self-contained and easy to drop into /usr/local or underneath OpenDKIM's or root's home directory. It's not something that needs to be routinely available either, once it's set up the entire process should be hands-off unless errors crop up.