update:
The system report is the results of running
>system_profiler
This simple command contains the current status of just about everything system related. The application's reporter files (.spreporter) are found in /System/Library/SystemProfiler. There is a SPApplicationsReporter.spreporter file but the basic operation of running the command system_profiler doesn't appear to run this file while using the GUI does. I'm still looking for more information.
Many of you might want more information on certain files but I suggest looking at the System Profiler to see how much can be found using existing, simple applications.
As for browser plugins, they are normally found in /Library/Internet Plug-Ins making it a simple task to find them.
Excuse me if I'm trying to use the simple way to find things on OSX.
OSX provides a very simple method of displaying all applications using About this Mac/More Info as the front end to a System Report. Just need to figure out how the application finds everything. This also finds all devices including printers.