On the Inviqa techPortal today there's a new post talking about the New Relic monitoring service and what it has to offer PHP developers and their applications to help them manage things like performance and resources.

The performance of a web application plays a critical role in how an application is perceived by its users. It is important to measure it, identify the causes if it changes and react swiftly to any unexpected changes. This article describes an industry leading tool, New Relic, and how it can be used to monitor and improve your site performance. [...] New Relic is a real-time application monitoring service, providing various metrics about the performance of your production site, covering everything from application database queries through to the time it takes for the end-user to view a page.

They walk you through a "getting started" with the tool and how to get it running on your server - for PHP this means installing an "agent" extension and a local daemon for it to feed information back to. They then get into some of the data New Relic provides including application performance details, browser information, throughput and an Apdex score.