"Somebody has recently asked me for a review of an app that can allow students to easily create posters on iPad. Pic Collage is the best option I recommend. With Pic collage you can take a bunch of picture and make one picture of it.
Using Pic Collage you can combine your photos in different ways . Scatter photos onto the background of your choosing or create a grid of your photos. Take the best parts of two photos to make one great one. Create a panorama or a mosaic out of multiple photos. If a picture speaks a thousand words, you can tell a whole story in a single frame with this app."
Via John Evans