Check_MK is a complex addon for Nagios/Icinga and consists of three subprojects. The check and inventory system Check_MK is a general purpose Nagios plugin for retrieving data. It adopts a new approach for collecting data and obsoletes NRPE, check_by_ssh, NSClient, and check_snmp. It features a significant reduction of CPU use on the Nagios host and automatic inventory of items to be checked, and is especially useful with larger Nagios installations. "MK Livestatus" gives immediate and fast access to live and historic Nagios status data. It's a supported backend for many addons including NagVis, NagiosBP, and Thruk. "Check_MK Multisite" is a feature complete replacement for the Nagios GUI, and uses MK Livestatus as a backend. It is very fast, and supports efficient distributed monitoring.
Lilac is a configuration tool for Nagios 3. Its features include enhanced Nagios 3 time period support, multiple template inheritance, host templates able to contain services, dependencies, and escalations, an importer which can import existing Nagios configurations and import from a Fruity installation, an Exporter with Nagios process control, the ability backup existing configuration files, and an auto-discovery tool to quickly add your infrastructure into your Nagios installation.
The Ninja project is an attempt to develop an alternative Nagios GUI with the aim of being the most useful Open Source Web front end for Nagios. It improves searching and filtering and scalability. It supports templates and skins for customizing appearance, and supports several databases. You can use the components of Ninja in combination with the CGI scripts of the original Nagios Web GUI or as replacements for them.
Nagios 4 iPhone is a Nagios interface for the iPhone. It does not require any modifications on your Nagios servers. The server part of this software collects statistics on several Nagios servers, serves a few static files, and generates a JSON response. The client part handles the display of the data on the iPhone.