Here's a new solution to an old problem. How to view slides, transparencies or X-rays without a light box? Light Pad HD (US$1.99) lets you see those old slides and other analog photographic media without lugging around a separate light box.
I have to admit, I have boxes of 35mm slides left over from my film days. Sorting them is a pain, holding them up to a lamp or a window is pretty cumbersome. Light Pad HD makes the process easy. Set the app up for the size film you have, or create your own custom size. In 35mm mode, there is room for six slides, and each pane can be turned on or off if you aren't viewing six at a time so glare can be eliminated. Four slides fit on an iPad mini.