Peter Aba has put together a a set of visualizations around the popularity of various PHP projects using the phpmetrics tool. He decided to run it against several projects he knows of and share the results.

I came across a new tool called phpmetrics. It can be used for, what a surprise, calculating and displaying metrics for php. I fell in love with this cute little tool in an instance and decided to run it on some php projects that I consider important. I’m aware of the fact that the list is currently far from complete, but it’s probably still worth a look. I especially love the “maintenability” (sic!) reports, I find those big red spots just as disgusting as I find ugly code the same.

He's broken it up into a few different sections with lots of different projects under each:

• Frameworks
• CMS
• E-commerce
• Development tools

There's also an "Other" (and "Backfire") category that contains the results for the results of phpmetrics itself. He also includes a few issues he ran across during the processing of the metrics, some with the phpmetrics tool itself and some with the libraries themselves.