Just an idea I've been thinking about for a while.
I live in the UK and I've found that diapers aren't always that easy to find. Up until recently the only shops around me that I knew that sold diapers is a handful of mobility shops aimed at old people.
I drive around a lot for my job so just out of curiosity I started checking any pharmacies I came across. To my surprise there are quite a few places stocking premium brands like Tena.
Getting to the point, wouldn't it be cool if we could gather all this information in an iPhone app/online service? Using the magic of gps you could search for who stocks what in your area.