While I can't personally attest to how well it actually works the mindset behind Groupshot is stellar. Basically it's an iOS photo merging app that lets you selectively choose faces from a number of photos to create the ultimate, perfectly posed, photo. I imagine anyone with a family, particularly small children, would find this to be a rather convenient way to create the perfect image... though there's something to be said for the amusement of a kid acting up in a photo when you look back at it 20 years later.