Webmin is a web-based interface for advanced system administration.
Using any modern web browser, advanced users can setup user accounts, Apache, DNS, file sharing and much more. Webmin removes the need to manually edit Unix configuration files like /etc/passwd, and lets you manage a system from the console or remotely.
Webmin has a modular structure and has a number of modules to manage your system.
Details on the standard modules of Webmin.