rfs is a shell script for creating and updating a local spare system disk. The main goal is to recover a working system after a crash quickly. In this case, "quickly" means the time it takes to reboot the machine. rfs stands for "replication of filesystems". Like rsyncbackup, rfs is built on top of rsync.
GNU ddrescue is a data recovery tool. It copies data from one file or block device (hard disk, CD-ROM, etc.) to another, trying to rescue the good parts first in case of read errors. GNU ddrescuelog is a tool that manipulates ddrescue logfiles, shows logfile contents, converts logfiles to/from other formats, compares logfiles, tests rescue status, and can delete a logfile if the rescue is done.
Grml is a live system (live CD) based on Debian. It includes a collection of GNU/Linux software especially for system administrators and users of texttools. It provides automatic hardware detection and its default shell is the zsh. You can use it e.g. as a rescue system, for analyzing systems/networks, or as a working environment. It is not necessary to install anything to a hard disk; you don't even need a hard disk to run it. Due to on-the-fly decompression, it includes more than 2 GB of software and documentation on the CD.
kmp_search is an extremely fast exact string search utility that can be used to search for exact strings or patterns in binary and text files and devices. It can search for multiple strings concurrently, but is much faster when searching for strings one-by-one. The starting byte offset of each match is reported to stdout. Because it is extremely fast, it can be used in a data recovery process after a multi-gigabyte file system crash. The Knuth-Morris-Pratt algorithm is used for the search, which gives a total time of O(file length + pattern length).
pxe-boot is a PXE boot configuration of a Red Hat kickstart environment and another PXE boot environment of a recovery console. The Red Hat kickstart is just the standard Red Hat install boot disk (ES3.0), but it does not come with the installation files, just the install environment. The recovery console is an edited Gentoo environment with raidtools, parted, partimage, lilo, grub, and a slew of other handy recovery tools.
Goodgoat Linux is a simple to use Linux distribution that can be run from a USB drive, hard drive, or CD-ROM. Rather than overwhelming users with a multitude of applications, it aims to have the best utility for each job. In addition to including the latest software, it makes it easy to share a computer's hard drive over a network.