Atomia DNS - Atomia DNS is a free & open source DNS management system.
cPanel - With its first-class support and rich feature set, cPanel & WHM has been the web hosting industry's most reliable, intuitive control panel since 1997.
facileManager - facileManager is a modular suite of web apps built with the system administrator in mind. Say good-bye to manual management of services running on multiple servers.
Webmin - Webmin is a web-based interface for system administration for Unix.
Vesta Control Panel - – What I love about Vesta is that it's fast and easy to use
Admin4 - Admin4 is a tool for server maintenance via several plugin modules, running on Windows, Mac OSX, Linux and many more platforms. Currently, plugins for BIND DNS, LDAP, IMAP and PostgreSQL are included.