How can I remove remnant processes from deleted preference panes?
Many preference pane applications also have background processes or kernel extensions. Removing the preference pane doesn't remove them, so you have to run an uninstaller or delete the files separately.

Background processes are often started by launchd services in the LaunchDaemons or LaunchAgents folders. You can remove them by just deleting the property list files (and restarting or logging out and back in). Some applications add login items that can be removed in the Users &amp; Groups preference pane.

The executables for the background processes are often somewhere in the root or user library, but they don't necessarily have to be removed.

Kernel extensions (in /System/Library/Extensions/) can also be removed by just moving them to the trash.

You can use Consultant's Canary to print a list of components that didn't come with OS X.