From Marcel Bresink Software-Systeme:
PrefEdit is an application to manage nearly all aspects of the preference system contained in every Mac OS X installation. The program consists of three components which are tightly integrated with each other: A browser and editor for the Mac OS X preferences database, a browser and editor for Mac OS X property list files (plists), and a browser for preference manifest files. PrefEdit was the first preferences editor ever published for Mac OS X. With its long experience and maturity, it has become one of the most advanced preference management applications for Mac OS X available today.
What's new in this version:
Added new feature to keep track of customized file name extensions for property list files that don't use the default extension. This prevents OS X from auto-correcting file names when changes are saved.