Cpanel

cPanel is a graphical, Web-based hosting control panel. Created and distributed by cPanel Inc., cPanel handles all aspects of Web site administration in one easy to use interface designed for end users.

Some useful links:

http://www.cpanel.net/support/docs/index.htm
http://www.eth0.us
http://forums.cpanel.net

Ensim

Ensim Pro is a automation control panel that enables service providers, resellers and Web site owners to centrally control and automate many shared hosting tasks.

Some useful links:

http://www.ensim.com/products/pro/linux/index.html
http://forum.ensim.com

Plesk

Plesk is comprehensive suite of server management and automation software developed for the Web hosting industry. Plesk is created and distributed by Parallels, Inc., formerly SWsoft.

Some useful links:

http://www.swsoft.com
http://forums.swsoft.com

Webadmin / Virtualmin

Webmin is a system configuration tool for Unix-like systems. It has a web-based graphical user interface for configuring some of the internals of the operating system.

Webmin is largely based on Perl, and is running as its own process, and web server. It usually uses TCP port 10000 for communicating, and can be configured to use SSL if OpenSSL is installed.

Some useful links:

http://www.webmin.com
http://www.virtualmin.com

VHCS

VHCS is a freely available, open source hosting control panel and automation tool designed to mimic paid control panel solutions, such as cPanel.

Some useful links:

http://www.vhcs.net
http://vhcs.net/new/modules/phpwiki/

ISPConfig

ISPConfig is a software package that permits the easy management of servers, webspace, resellers and single virtual hosts.

Some useful links:

http://ispconfig.org/downloads/manual_en/toc.html