I recently upgraded from fckeditor.module 5.x-1.2 to 5.x-2.2rc7. I was having some issues with the upgrade, so I decided to uninstall the upgraded fckeditor-2.2rc7. After the re-installation of fckeditor.module, I noticed that some of my old settings were still there. It seems that the uninstall did not remove the settings from drupal_variables. Here is a list of setting that are left behind.