This is an awesome free iOS app that allows users to easily create photographic works of art. It is very easy to use and has a user friendly interface. It also lets users share their creations with their friends and colleagues via email or Facebook.
2- Picture Collage HD
This app allows users to make a collage of all their selected pictures into one. Users can move, rotate and change the size of the pictures within the collage and finally share it with the world using email or MMS.
This one here is more of a remix tool of your photographs than a traditional collage marker. It is ideal for creating narratives and telling stories. It also allows for a different set of sharing options.
4- Sadun's Collage
Collage is fun a app to use. You can pinch, zoom, and drag live camera feeds to create art. It also lets you make simple and easy collages of pictures in your library.