tarmill is a tar file compression/encryption program.
tzls and tzx
tzls and tzx are commandline utilities for quickly unpacking or listing the contents of various types of common Unix archive files, which may be compressed in any of several ways.
unace is a utility to extract, view, and test the contents of an ACE archive.
unADF is an unzip like for .ADF files. Powered by ADFlib.
UPX is a free, portable, extendable, high-performance executable packer for several different executable formats. It achieves an excellent compression ratio and offers very fast decompression.
Xarchiver is a GTK+2 only frontend to 7z,zip,rar,tar,bzip2, gzip,arj, lha, rpm and deb. Xarchiver allows you to create, add, extract and delete files in the above formats. 7z, zip, rar, arj password protected archives, sfx and solid archives, archive comment are supported.
xmlppm is a data compression program that compresses XML files from 5 to 30% better than any existing text or XML-specific compressors.
XZ Utils is open source general-purpose data compression software with high compression ratio. Read more
Zopfli Compression Algorithm is a new zlib (gzip, deflate) compatible compressor. This compressor takes more time (~100x slower), but compresses around 5% better than zlib and better than any other zlib-compatible compressor we have found.