Free Tilt PDF is a great little app that has a lot of potential uses. In the video below, you can see how, by adding images instead of text (the usual kind of PDF file) a lot of interesting interactivity can be added into a creation. You might need to get the image size just right by cropping it. (Try GIMP (free) if you don’t want to buy photo editing software.) Get images from Google, Flickr, your camera, your photo roll, etc.
The rocks image in the video below can be found here. (Right click to save.)
Get the rock image used in the above video here. It’s a pdf file. Then put it into Free Tilt Pdf. (Right click and “Save Target As…” to download.)