This is a slightly modified version of NPSPY that ships with Firefox, plus some logging and bug fixes.
NPSPY sits between the browser and plugin and allows logging of all NPP_* and NPN_* function calls
along with their parameters.

To use this, place this in Chrome\plugins or Firefox\plugins depending on which browser you want to log.
Note that NPSPY will look for the real plugin in the running browser's plugins directory.  So if this is
placed in Chrome\plugins, plugins that are located in Firefox\plugins won't be found.