Adagios is a Web-based Nagios configuration interface built to be simple and intuitive in design, exposing less of the clutter under the hood of Nagios. It has a REST interface for both status and configuration data as well a feature complete status interface that can be used as an alternative to the Nagios Web interface.
check_mssql_health is a plugin for Nagios that allows you to monitor an MS SQL Server. Among the list of metrics are time to login, buffer cache hit rate, page life expectancy, full table scan rate, free space in databases, batch requests/second, and many more. Installation of the DBD::Sybase Perl module is required.
Upsilon is a distributed, flexible, and extensible system monitoring application. Being distributed means you run service checks on Upsilon nodes in your network where it makes sense, either on every server or on a management network, inside or outside the firewall. You can run checks on secure, hard to reach networks, and push those results to a central server. You can optionally execute "agentless" checks just by using SSH. Being flexible means that if you can script it, you can monitor it. Unlike most monitoring systems, the monitoring scripts are external to the main server, so you can use Upsilon to execute your monitoring scripts in an extremely robust way. Upsilon has been used to monitor many different things and is API-compatible with all nagios monitoring scripts. Being extensible means you can add monitoring checks to Upsilon at runtime without needing to restart the server. The upsilon-node and upsilon-web projects both have their own REST APIs.
CoffeeSaint is a Java application that shows the status of Nagios (version 1 up to 3 and the newer XI) on a screen. It can, if there are no errors, display a Webcam feed. If an error status occurs, it can play a sound. One can configure it to display certain errors/warnings always on top. It is remotely configurable via a built-in Web interface.
SysopView shows information in a visually attractive way, like computers in movies do. The idea is that it can show information relevant to system administrators non-comprehensible for non-technical personnel, while still looking attractive even if you don't know what is shown. The current version can show nagios status data, webcam streams (mjpeg, jpeg, and video4Linux), and VNC, has a built-in terminal emulator in which regular text applications can be run, can sniff the network (including remotely) and dissect streams and show pictures which are sniffed, can show external bitmaps (from, for example, mrtg and rrdtool), and can scroll text (currently showing output of rssfeeds).
check_nwc_health is a plugin for the Shinken (or Nagios/Icinga) monitoring system. It is used to check hardware health, environment, interfaces, pools, uptime, etc. of a great range of the most popular network components like switches, routers, firewalls, proxies, load balancers, etc. Currently it can monitor: Cisco IOS, Cisco Nexus, F5 BIG-IP, CheckPoint Firewall1, Juniper NetScreen, HP Procurve, Nortel, Brocade 4100/4900, EMC DS 4700, EMC DS 24, Allied Telesyn, and Blue Coat SG600.
jmxtrans is effectively the missing connector between JMX and whatever logging or graphing package that you can dream up. jmxtrans is very powerful tool that reads JSON configuration files specifying servers/ports and JMX domains/attributes and then outputs the data in whatever format you want via special "Writer" objects that you can code up yourself. It does this with a very efficient engine design that will scale to querying literally thousands of machines. The core engine is pretty solid and writers are included for cacti/rrdtool, graphite, and stdout.
Nagios has been around for quite some time, but producing output it can consume is something of a black art. Only the plugin documentation actually explains what all the extra semicolons or extended formatting even mean. This is especially onerous when performance consuming add-ons expect a specific structure before operating properly. The NagAconda package strives to greatly simplify the process of actually generating Nagios output using Python.