p7zip is the Mac version of the popular Windows decompression application
However, there is a user interface provided by a separate program called
The great thing is that p7zip supports a huge number of compression formats so it's very flexible. The obvious downside though is that it only runs using command lines. For more information on the available commands, simply type /Volumes/p7zip/7za in the Mac terminal.
p7zip is a powerful compression tool that is ideal for those who know how to use Terminal, but will prove tricky to understand by many due to the lack of user interface.