Seconded. The Unarchiver is always one of the first things I install on a new Mac. The same author is also responsible for another program, Xee, which is a gre

Seconded. The Unarchiver is always one of the first things I install on a new Mac. The same author is also responsible for another program, Xee, which is a great, no nonsense image viewer. The 3.x version costs a few bucks, but the last 2.x version can still be downloaded for free.