Zabbix
Zabbix is an enterprise-class open source distributed monitoring solution designed to monitor and track performance and availability of network servers, devices and other IT resources. Zabbix possesses a flexible notification mechanism that allows users to configure e-mail, Jabber and SMS based alerts for any kind of event which helps administrators to recognize server and device problems faster. Zabbix is being developed non-stop and its number of functionalities and performance is increasing rapidly with every new version release.