In the pre-iPhone era, iTrek was born out of a real need -- I was heading for a vacation to the Pacific Northwest in Canada and had carefully chalked out my entire itinerary using Yahoo! Trip Planner. To avoid printing out a big stack of papers with the itinerary, this hack involved creating a grease monkey script that would allow users to save their entire itinerary in a format that would port beautifully to an iPod.
Since the iPod is so unique in its interaction using the jog/shuttle and in its navigation, I converted the itinerary into a hierarchal tree navigation structure that was easy and intuitive to uses on the iPod. iTrek won the His Steve-ness award on Yahoo! Hack Day in Fall 2006, the award being named in honor of Steve Jobs.