The Sleuth Kit is a C++ library and collection of open source file system forensics tools that allow you to, among other things, view allocated and deleted data from NTFS, FAT, FFS, EXT2, Ext3, HFS+, and ISO9660 images.
For cleaning the Windows system registar from obsolete registrations e/o removing all the items associates with an unistalled application and removing all the unnecessary registrations leaved by applications that huge the system registar.
ZZ is an open-source WinFS. ZZ relies on the same fundamental idea as WinFS, namely that a graph-oriented data store is more user-friendly than the usual tree model.
TriOS - The Object Oriented Operating System, is the next generation operating system. Fully based on object orientation, it brings unique features to programmers and end users. Basically everything in TriOS is an object, even files and programs! Enjoy!!