I have used webmin for quite some time now, both at home and at work. I think it is a wonderful package for managing the computer, especially for newcomers to linux/unix. It has simplified tedious tasks like dns configuration, version control, database configuration, network configuration, etc. It has a pleasent GUI environment, easy to navigate around, and you can do most of your system admin with it.
in reply to Installing perl modules via webmin
Security wise, I never had any problem about running webmin on the LAN. However I am a bit skeptical about exposing the webmin access port to the internet, even when the webmin is configured to run in HTTPS mode. There are too many brilliant hackers out there, you never know what might happen next.