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.
The Merlin project was initially started to create an easy way to set up distributed Nagios installations, allowing Nagios processes to exchange information directly as an alternative to the standard method using NSCA. It has also been extended with fault tolerance, the ability to store status information in a database, and other features. This allows Merlin to function as a backend for applications such as the Ninja project.