Microsoft is doing some amazing work with very large images and collages consisting of massive numbers of images that are related, under the banner of Sea Dragon. As they put it:

The aim of Seadragon is nothing less than to change the way we use screens, from wall-sized displays all the way down to cell phones, so that graphics and photos are smoothly browsed, regardless of the amount of data or the bandwidth of the network.

Today they launched their iPhone application which looks pretty cool. Check it out on iTunes, it’s very impressive how fast and how deep you can zoom in and out of pictures. They provide a whole set of sample images for impressing your friends and you can browse Photosynth sets too.