For those short on budget, there’s a very light and powerfull free app called The Unarchiver. It allows you to extract many more file formats besides the .zip, such as .tar-gzip, .tar-bzip2, .rar, 7-zip, .lhA and stuffIt. Also it better handles filenames from foreign character sets, created with non-English versions of other operating systems.
The installation is very simple: copy the applications into your Applications folder and start using the application. The Unarchiver requires Mac OS X 10.3.9.
