a few years ago i started to scratch together a php/mysql based database for pure-data documentation, the project became eclipsed by the push to the wikimedia based pdpedia, so i didn't get much further than documenting vanilla objects, and integrating the csv doc by marius schebella. but the one thing i did do was break the list into categories and subcategories.
my intention at the time was to collate enough information in the database to be able to publish the entire thing as a pdf reference, but i was also thinking of integrating the database into desiredata for contextual help. the most information present is for the vanilla set (pd-lib) with info on the internal methods for inlets and outlets.
the tool itself while far from complete was useful enough as a quick reference guide, especially when i wasn't connected to the internet.. it sports a zippy interface that 'expands' dynamically, and basically attempts to resemble 'help-intro.pd'. anyhow it was lost on an old disk image, but i have managed to revive it and install it on my current machine..
i don't know if its useful to anyone, but its relevant to this thread and documents my interpretation of object categories.. so if its of interest, please point your browser to: http://dmotd.dyndns.org/pd/objects.php i've also made a backup of the sql table: http://dmotd.dyndns.org/pd/pure-data.sql OR http://dmotd.dyndns.org/pd/pure-data.csv
(i don't have access to an actual server at present, so i will leave this open for a few days.. please be kind to my machine!)
cheers, dmotd