XDebug is really useful for debugging PHP, which is usually not really easy to debug, and also easy to install.
It provides a lot of valuable debug informations, for example a full traceback for errors, profiling with memory and CPU usage, profiling functions, etc.
I really suggest to take a look at it! Both Windows and Linux versions are available for download.
In these days, working with PHP after a lot of time, I've installed this cool tool for debugging PHP (it supports both PHP 4 and 5).
You can grab the latest version (0.9.0 or 2.0.0beta5) directly from the right-hand side of their site.
