MacPorts is a system for compiling, installing, and managing free and
open source software. A MacPorts "port" is a set of specifications
contained in a Portfile that defines an application, its characteristics,
and any files or special instructions required to install it, so MacPorts
may automatically fetch, patch, compile, and install ported software.

MacPorts may also be used to pre-compile ported software into binaries
that may be installed on remote computers. Binaries of ported software
may be installed very quickly since the steps required to install ports
from source code have all been performed in advance.

WWW: http://www.macports.org/