openpom is a Web interface based on NDO for Nagios or Icinga. It allows you to view almost everything about Nagios or Icinga in a single page: alert, ack, downtime, comment. You can also interact with Nagios or Icinga through ack, downtime, comment, disable, and reset buttons. You can filter on hosts and services states (such as critical, warning, unknown, ok, or outage). The status popin allows you to display graphs, either the ones from Nagios (trends.cgi) or custom ones based on RRD (such as pnp4nagios).
Shinken is an advanced monitoring system that is based on Nagios, but redesigned and rewritten from scratch while maintaining compatibility. It can monitor all IT devices from systems to end user applications. In case of a failure, Shinken can alert the operation engineers so they can promptly repair it. It has the same capabilities as Nagios along with more advanced built-in facilities such as load balanced and high availability monitoring.