One of the nice things about the Airport Extreme Base Station is the Airport Utility application used to manage it. Most other routers these days are managed with a web interface which can sometimes be a little wonky. So it was with some interest that I discovered Port Map, from the Coding Monkeys of SubEthaEdit fame.
Port Map is not a full-fledged management application, but it does bring Cocoa lickability to one standard management task: port mapping, an essential task for iChat or Back to my Mac. If your router supports UPnP / NAT-PNP Port Map provides an iPhone-esque Ui for setting up specific ports, including "presets and URL templates." You can see it working above with my DD-WRT Linksys router (don't worry, I turned it off after the screenshot).
Port Map is a free download from The Coding Monkeys. They've also open-sourced some of the coding goodness that makes this possible and created a framework available to other developers on a Google Code page.