This is a screenshot of the development dashboard I built on top of our Zend Framework / ExtJS based web app. http://i.imgur.com/3d9sqFa.png http://i.imgur.com

This is a screenshot of the development dashboard I built on top of our Zend Framework / ExtJS based web app. http://i.imgur.com/3d9sqFa.png http://i.imgur.com/3d9sqFa.png The sparkline in the bottom status bar lets you keep an eye on server request performance (single page app), and clicking it allows to see the details of the past 100 requests, including what DB calls were made and what parameters were used (great for finding slow queries and pulling them out to test and tune in isolation). The server tab gives overall php server and database statistics. Our product has gotten a lot faster since integrating this, and I don't think that's a coincidence. It is extremely useful, and not just for performance optimization.