Afio makes cpio-format archives. It deals somewhat gracefully with input data corruption, supports multi-volume archives during interactive operation, and can make compressed archives that are much safer than compressed tar or cpio archives. Afio is best used as an `archive engine' in a backup script.
bzip2 is a portable, lossless data compressor based on the Burrows-Wheeler transform. It achieves good compression and runs on practically every (32/64-bit) platform in the known universe. The compression engine is also available as a library (libbz2), should you desire a programmatic interface.
fistgen is the FiST language code generator, used to create stackable file systems out of templates and a high-level language. This package comes with stackable file system templates for Linux, Solaris, and FreeBSD. It also contains several sample file systems built using the FiST language: an encryption file system, a compression file system, and more - all of which are written as portable stackable file systems.