On the SitePoint PHP Blog Troels Knak-Nielsen has worked up a way to "expose PHP's private parts" when it comes to finding out more about the object/variable he's working with (without a usual print_r or var_dump).
I've been tinkering with dumping PHP objects, and have found myself constantly running into a brick wall. The output from print_r and friends is fine in some contexts, but for larger structures, it would be nice to tidy the output up a bit and wrap it in some HTML.
His solution is to serialize the object into a string (keeping all related meta information) that can be passed around and parsed back into its original form for debugging. He's included the script that works bye taking in the string and manually parsing it back out into its parts into a useful array.