Webmin is an excellent web-based interface to your *nix based machines. There are no webmin packages in the latest release "Dapper". This is how to install webmin to a Dapper server install...
(Update 2/24/2008: I do this on versions of Ubuntu up to the latest beta release also or on Debain (etch, lenny so far))

1. Install SSH

apt-get install ssh

2. Enable the universe and multiverse repositories in the /etc/apt/sources.list (https://wiki.ubuntu.com/AddingRepositoriesCliHowto)