Clean-Install Assistant 1.1 was just released :

Clean-Install Assistant makes it easier to migrate third-party and personal
items to a new Clean-Installed System Folder, and it may also be used to:

Save space and backup your valuable additions and preference files
only, instead of the whole System Folder.

Install the same set of additions on multiple Macs.

Remove extra files and folders from your System Folder to restore it
to a previous state: you can take a ‘snapshot’ of the System Folder
and have Clean-Install Assistant extract any items added since.

Version 1.1 adds support for Mac OS 8.5 and allows migrating files from
previous System Folders as well as active ones. It is free for personal and
educational use, download from http://www.marcmoini.com