2 thoughts.
#1. A phone App that tells you what fish you can eat and which ones you should avoid. This tool would be great for pregnant woman, since they're suppose to eat fish, but many don't know which ones. Me included - not the pregnant part, the which fishes to eat. I think this idea would suit a pregnancy magazine or even maternity store (Get it free with purchase).
#2.An App that calculates your carbon footprint. I'm sure it already exists, but I just read this article about Tropicana putting carbon footprint data right on their packaging. Imagine you can scan bar cones throughout your day and at the end go online to see how much impact you had. Maybe there's a more positive spin......