Or, if your development environment supports dotty (the interactive dot environment from graphviz), you can install Devel::Command::Viz and get pictures of your data structures drawn with dot by GraphViz::Data::Structure.

Disclaimer: I wrote both of these and for the two or three times I've really needed them, they really helped.

Sometime I should tell the story of how wanting to do this got me into completely recommenting the debugger...