Compression

Allume Systems
Makers of the Stuffit suite of compression utilities. Such programs include Stuffit Expander, a freeware expander, and Stuffit Deluxe, the company's ultimate utility for compression and seamless Finder integration.
http://www.allume.com/

ColdCompress
A simple and graphical .tar.gz compression program for Mac OS X Server.
http://www.stepwise.com/Software/ColdCompress/index.html

Compact Pro
A shareware file compression utility that provides segmented archive and encryption features.
http://www.cyclos.com/compactpro.htm

MacBzip2
a freely available, patent free, high-quality data compressor. It typically compresses files to within 10% to 15% of the best available techniques, whilst being around twice as fast at compression and six times faster at decompression.
http://persephone.cps.unizar.es/~spd/bzip2/

MacGzip
A freeware compression utility based on open source code.
http://persephone.cps.unizar.es/~spd/gzip/

MacTar
A Mac OS port of "tar" (tape archive), a common file-packing format used on Unix machines. This program reads and writes tar format archives.
http://www.strout.net/macsoft/mactar/

MacZip
Describes status of development and porting efforts.
http://www.haase-online.de/dirk/maczip/

Mindvision
Creator of Mac file compression, installation, and decompression programs.
http://www.mindvision.com/

OpenUp
A powerful compression program by Scott Anguish for Mac OS X Server and OpenStep that can expand a large variety of common and uncommon compression formats.
http://www.stepwise.com/Software/OpenUp/index.html

PackUpAndGo
A drag-and-drop compression program by Stone Design for Mac OS X Server or Yellow Box for Windows.
http://www.stone.com/PackUpAndGo/PackUpAndGo.html

ZipIt
Full-featured Macintosh shareware utility to compress files in the zip format.
http://www.maczipit.com/