Mitsuharu Arimura's Data Compression Pointers
Very large list of links, including books and lecture notes, benchmarkings, archives, image/graphic compression, fractal compression, wavelets, video and audio compression, and links to other link lists.
http://www.hn.is.uec.ac.jp/~arimura/compression_links.html

Maximum Compression
Maximum compression features reviews/benchmarks designed to show/test the best lossless data compression software (mainly command line compression programs).
http://www.maximumcompression.com/

Data-Compression.com
A website devoted to the principles and practice of data compression.
http://www.data-compression.com

Redstone Compression Conference
Workshop on Data Compression Processing Techniques for Missile Guidance Data Links. Redstone Arsenal, Alabama, USA; 2--3 December 1998.
http://smaplab.ri.uah.edu/dc/

Data Compression ActiveX and DLL Components
Makers of DynaZIP and Active Delivery Zip Data Compression and Self-Extract ActiveX, DLL, VCL, VBX Component Library with ASP support, all royalty free.
http://www.imiwebs.com/

Strutz, Tilo
University of Rostock, Signal and Image Processing group. Research interests: Data compression, Systematisation. Software, papers and textbook on Image Data Compression.
http://www-nt.e-technik.uni-rostock.de/~ts/

Official International WinRAR Website
Windows data compression utility that focuses on the RAR and ZIP data compression formats for all Windows users. Supports CAB, ARJ, LZH, ACE, TAR, GZIP, UUE, BZ2, JAR and ISO format. Bilingual web site.
http://www.win-rar.com/

The Art of Lossless Data Compression
Results of tests performed to compare lossless compression of various data by all known good enough programs. Descriptions of test terms and files. Links to related programs, and pages.
http://geocities.com/SiliconValley/Bay/1995/

Crusher Data Compression Toolkits
High-performance, portable data compression libraries for Windows, OS/2, Unix, DOS, and Macintosh developers. Crusher's comprehensive API of 45+ functions, identical across all platforms, provides buffer compression, file compression, archiving, subdirectory support, wildcards, disk spanning, encryption, self-extracting EXE's and more. Typical results compresses data to 20-50% of their original size or less. Implement full archiving in just four function calls. Crusher archives are portable across all supported platforms and full source code is included, as well as numerous sample applications. Includes ARQ.EXE, a convenient command-line utility for managing Crusher archives, and SETUP, a Windows installation/setup program.
http://www.dcmicro.com/crusher/

ACM Crossroads Data Compression Issue
ACM Crossroads 6.3: Data Compression
http://www.acm.org/crossroads/xrds6-3