I've recently started using Fink and Darwin / Mac Ports recently, and they have improved so much over the past few years. From being totally isolated in the filesystem to the full integration with X11, its really amazing how close to being a linux machine a Mac machine can be. If you like linux and Macs and haven't tried out these great open source tools yet, do so today! Know debian? You'll find yourself completely at home with Fink. Got BSD? You'll hit the ground running with Mac Ports. When researching accounting programs for an open-source accounting system I'm working on, I used Mac Ports to install GnuCash on my Macbook. It took forever, but it worked 100%. Now if we could get Gentoo for Mac OS X working correctly... last time I tried that it royally screwed up my machine. :-(
Gentoo is cool though, kind of like ports for linux. Here's a good simple MacPorts and Fink update script.