Portage
From Applepedia
Portage is the package management system developed for Gentoo Linux, and it has been ported to OS X and other unixes. More projects like this are listed in the Unix/X11 section of Software Gold. Portage for Mac OS X is part of the Metapkg Alliance.
There is a Gentoo wiki entry on portage over OS X, as well as an official website and some official documentation on the project.
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