Ftwalk is a high level script programming language, very similar to awk, but greatly extended to include a richer type system, object-oriented features, 300+ built-in functions, extensibility through dynamic libraries, etc., which makes it roughly comparable to languages like Perl. It does file tree searches, and was originally used to implement selective redundant copy backup stores. It can be run interactively as a calculator.
Star is a very fast, POSIX-compliant tar archiver, maintained for more than 30 years. It saves many files together into a single tape or disk archive, and can restore individual files from the archive. It includes command line interfaces for the "tar", "Sun-Tar", "cpio", "pax", and "gnutar" command-line syntax. It includes a FIFO for speed, a pattern matcher, multi-volume support, the ability to archive sparse files and ACLs, the ability to archive extended file flags, automatic archive format detection, automatic byte order recognition, automatic archive compression/decompression, remote archives, and special features that allow star to be used for full and incremental backups. It includes the only known platform independent "rmt" server program.
Xfiles is an interactive utility for comparing and merging one file tree with another over a network. It supports freeform work on several machines (no need to keep track of what files are changed on which machine). Xfiles can also be used as a cross-validating disk<->disk backup strategy.
rsync-backup automates the process of backing up multiple systems to one or more backup servers. It focuses on making the process secure. It encrypts the backup going across the wire, only ships changed data, runs the server as root to preserve permissions and ownership, keeps people from seeing each other's backups, and doesn't require the server to trust any files sent from the clients. It doesn't ship password files, key files, nor other sensitive files across the wire, but backs them up locally instead. Admins may use one key for everyone (backups named after the client IP) or allow named backups (when a machine may change IP or when multiple independant backups may need to be made from one machine).
Selected Backup uses include and exclude files to provide an efficient method of backing up a list of files and directories. It uses tar and gzip, and has an option to email the attached file to an admin user. It is written in Perl, and has a number of options, including the ability to clean up files older than a certain age.
MySQL Backup is a Perl script that uses mysqlshow to grab the database names and "show tables" to grab the table names for a user's account, and then uses mysqldump to save the data in a subdirectory named in the script. It then tars and gzips the files, using the date and time for the file name. It can be run from cron on a daily basis. It removes old files and has an option to email the gzip file to an admin, and/or FTP the file to a remote server. It also has options to use "select data into outfile" or a regular "select" for users who can't use mysqldump. It supports LARGE sets of databases and tables.
REOBack Backup Solution (pronounced "Ray-o-back") is a simple backup solution designed for Linux users and system administrators. It is designed to be simple to set up, and easy to use. It is great as a quick solution for those who procrastinate about backups. It supports automatic full/incremental backups of files you define, remote backups via SCP, SMB, NFS, or FTP, as well as auto deletion of old backups.