At some point in the release cycle, Webmin added support for both OS X and OS X Server, which means that everything works as expected under OS X. Installation is trivial; download the package, put it where you want it to run from, and then type
sudo ./setup.shto run the setup script. You can use the default answers to every question, just make sure you pick the correct OS from the list (OS X is number 40). It even supports versions 10.0.x and 10.1. It even comes with a nice uninstaller. Just type
sudo /etc/webmin/uninstall.shand it will stop the server and remove itself from your system.
I highly recommend Webmin as an easy way to administer the UNIX side of Mac OS X. Be careful, however, as you can easily change some things that may have unintended consequences ... that's the downside of easy access to everything!

