A way back I've written myself a small application to make geocaching easier to manage. It downloads geocache information, converts to gpx format (some sort of xml understood by the GPS device) and then writes to the GPS device - (Garmin Colorado) via USB. It's not really an application I'm proud of, it's full of hacks and the UI is also of stone age usability, but so far I wasn't able to find a better one.
Anyway, my wife suggested I install the app on her computer as well, so that she can upload a cache even when I'm not around. I've always run the app from command line or from the IDE, but that's not something I want my wife to go though :) Since she has a Mac laptop, I've looked into how to generate a Mac natively executable binary. It was easier than I though thanks to the wide and deep reservoir of Apache Maven plugins around. There is one for Mac applications as well - osxappbundle-maven-plugin. A simple copy&paste into my pom and there we have a nice geocaching.dmg file with the geocaching.app application. Great. The biggest obstacle turned out to be creation of the *.icns file with a custom icon for the application. It's created by the Icon Composer application (at /Developer/Applications/Utilities/Icon Composer) and it took me a while that it doesn't accept gif files but tiff image files. It's great when things just work and work in 15 minutes time..
And we've visited this geocache afterwards. A great trip.