Here is a list of 10 nagios 2.x web frontends that you might find useful if you are looking for a web interface to administer your nagios configuration.
1. Centreon / Oreon - http://www.centreon.com/ Centreon is a network, system, applicative supervision and monitoring tool, it is based upon the most effective Open Source monitoring engine : Nagios. Centreon provides a new frontend and new functionalities to Nagios.
2. Fruity - http://fruity.sourceforge.net/ Fruity is a web based application (PHP & MySQL) to make Nagios configuration easier. It provides a logical flow of your hosts with services and creates relationships between objects. It stores it’s configuration internally into a database and when you are satisfied with your configuration, you can then export it to nagios’s configuration files.
3. Monarch - GroundWork Monitor Architect - http://sourceforge.net/projects/monarch GroundWork Monitor Architect (Monarch) is a full-featured, easy-to-use configuration system for use with Nagios. Monarch consists of a set of tools that allow a user to easily configure and maintain Nagios, or GroundWork Monitor, without editing the Nagios configuration files directly.
4. NagiosQL - http://www.nagiosql.org NagiosQL is a web based administration tool for Nagios 2.x. It helps you to easy build a complex configuration with all options, manage them and use them. NagiosQL needs a webserver with php, MySQL and file access to the nagios configuration files.
5. NagiosWeb - http://sourceforge.net/projects/nagiosweb/ A PHP/MySQL based front-end for Nagios 2.x setup. Complete with the ability to add/remove hosts, hostgroups, contacts, contactgroups, services, timeperiods and commands.
6. NCPL - http://sourceforge.net/projects/ncpl/ NCPL is a webbased solution written in PERL for configuring Nagios. NCPL gives you centralized control over remote Nagios systems from a central server and permits to edit and install new config files. It uses MySQL to store configuration data.
7. Nagios Config - http://nagiosconfig.com/ Nagios Config is a FREE web front end to Nagios, written in PHP.
8. NagMIN - http://nagmin.sourceforge.net/ NagMIN is a WebMIN module that provides centralized, integrated, web-based management of popular Open Source monitoring tools to help create a holistic network monitoring environment.
9. nag2web - http://nag2web.de/ A PHP/MySQL web front-end for Nagios 2.x setup. With the ability to add/remove/edit the config items. The web front-end for NAGIOS has the ability to test the config. We want to build a simple possibility to find and show all the features in NAGIOS.
10. NaWui - http://www.stigma.dyndns.org/NaWui NaWui stands for Nagios Administration Web User Interface.It is a Web frontend written in PHP to manage Nagios configurations and Database records. Database connectivity is supported using plugins, which simplifies the way records are stored.
Source, where you can find many nagios interesting stuff: http://www.nagiosexchange.org/
ps: If you think I have missed a similar project and you want it added to this page, please feel free to use the contact form or the comments to let me know.