ESR Backup (Easy, Secure, Remote) is a backup system for UNIX and Linux that is easy to use and configure. It automatically performs full and incremental backups on files you choose, and automatically rotates and archives your backups, encrypts archives with a 448 bit key, and can store archives on a remote server via FTP or on the local file system.
myBackware is a set of scripts that create a regular set of database dump files for the disaster recovery of MySQL servers. It uses MySQL's mysqldump to create backups as either a filesystem-stored snapshot or as an email attachment. Either method has the option to compress and GPG-encrypt the dump file.
srzip is a compression utility with an interface very similar to gzip or bzip2. Its goal is not to compete with classic compressing and archiving programs, but to offer a framework for testing and learning about various algorithms. Algorithms implemented so far include run-length encoding, static and adaptive Huffman encoding, and Burrows-Wheeler transformation.