have you tried google??

I think webmin is enough for personal or few sites management.

I agree, i know many people that used to host at fasthosts and complain about huge downtimes and incredibly slow servers. When you do a few whois checks from whois.sc , you can see that fasthosts averagely hosts about 1500 web sites per server.

Webmin is a web-based interface for system administration for Unix. Using any browser that supports tables and forms, you can setup user accounts, Apache, DNS, file sharing and so on.

I think on a test / non production server they will do the job well but i wouldn't consider offering it to a paid-client.

Webmin is good. Webmin makes it easy to add new functionality, without too much work. Webmin also allows for controlling many machines through a single interface, or seamless login on other webmin hosts in the same LAN.

Usermin is only designed for general usage tasks, not just administration tasks.

I've used VHCS quite a bit for lower end servers. For customers who use only the basic functions of a control panel (about 85% of all customers), VHCS works very well. Configuration is simple in Debian, but a bit quirky in other flavors of Linux.

Cpanel, DirectAdmin, Plesk, Helm are the most common panels and they become the industry standard.