Hipsters like everything ironic and retro. That's why instagram was such a hit; it combines both. Obviously the photos look retro, and they're automatically ironic because each says "Hey look I have the latest in phone/camera technology, but all you see is what this picture would have looked like 40 years ago." That's what you have to keep in mind. Maybe an app that turns all of your photos into having graffiti/spray pain look. Or one that automatically adds a knit hat to any animal in the picture.