If you like, you can use Portage from Gentoo on OS X. It's not up to date for Leopard (which is why I didn't mention it before), but the option is there:
http://www.gentoo.org/proj/en/gentoo-alt/prefix/bootstrap-ma... - Though it requires slightly more then basic knowledge of a Bash (or $insertYourPreferredShell) to set up. There's also way's to use rpm5's on OS X - And there's patches to get dpkg working on OS X if you fancy apt.
But, again: Mac OS X is not Linux. Setting Portage up is a huge hack to hold things together though. So if you have the time to set a .deb or .rpm-based system up, you should really just get a Linux box to use instead and then take the time you saved and do something productive. At least thats what my experience tells me.