7-Zip is an open-source file archiver with a high compression ratio. On the packing/unpacking front, the freeware supports 7z, ZIP, GZIP, BZIP2, and TAR. As for its unpack-only support, 7-Zip is compatible with ARJ, CAB, CHM, CPIO, DEB, DMG, HFS, ISO, LZH, LZMA, MSI, NSIS, RAR, RPM, UDF, WIM, XAR, and Z.
While this seems to cover all compression formats, it's not a perfect science: 7-Zip may be able to unpack one ZIP file without a hiccup, the app may run into trouble trying to unload the next ZIP file. This should expected given the program's diversity and open-source-based roots.
Still, 7-Zip can be used on any computer, including those located in a commercial organization. It's definitely a great alternative to the premium offerings like WinZip, which isn't even threaded, and WinRAR.
Download: 7-Zip 9.15 beta