Freedup finds and eliminates duplicate files by linking them, and thus reduces the amount of used disk space within one or more file systems. By default, hardlinks are used on a single device, symbolic links when the devices differ. A set of options allows you to modify the methods of file comparison, the hash functions, the linking behavior, and the reporting style. You may use batch or interactive mode. Freedup usually only considers identical files, but when comparing audio or graphics files, you may elect to ignore the tags.
FreeOTFE4PDA is an "on-the-fly" (OTFE) transparent disk encryption program. Using this software, you can create one or more "virtual memory cards" on your PDA. Anything written to one of these cards will be automatically and securely encrypted before being stored. A PC version is also available, allowing data encrypted on your PC to be read/written on your PDA, and vice-versa.
GNU Parted is a package for creating, destroying, resizing, checking, and copying partitions and the file systems on them. This is useful for creating space for new operating systems, reorganizing disk usage, copying data between hard disks, and disk imaging. It contains a library, libparted, and a command-line frontend, parted, which also serves as a sample implementation and script backend.
GNU xorriso creates, loads, manipulates, and writes ISO 9660 filesystem images with Rock Ridge extensions. Files can be copied in and out. The session results get written to optical media or to filesystem objects. Rather than needing external tools for ISO 9660 production and CD/DVD/BD burning, it is a static compilation of libburnia-project.org. Thus GNU xorriso depends only on fundamental operating system facilities.
GNUnet is a peer-to-peer framework with focus on providing security. All peer-to-peer messages in the network are confidential and authenticated. The framework provides a transport abstraction layer and can currently encapsulate the network traffic in UDP, TCP, HTTP, HTTPS, or direct 802.11 (WLAN). GNUnet supports accounting to provide contributing nodes with better service. The services built on top of the framework include anonymous file sharing and a virtual network providing IPv4-IPv6 transition via protocol translation over the P2P network.