The SitePoint PHP blog has a recent post about an addition to the Symfony framework that can make debugging (or just outputting errors) a more pleasant experience: the VarDumper component.
Recently, Symfony went from Zend-like bloat and rigidity to extreme decoupling and modularity. [...] One factor that contributes to this factor a lot is their continuous pushing out of new components that are incredibly useful outside of Symfony's context. One such component is the new VarDumper.
He talks first about the "why" the component was created and why you might want to use it. He links to the documentation and what kinds of features come along with it. He also shows a quick install of the component, some usage of it in the code and the resulting output of both simple and complex data structures, including method structure, visibility and closure information.