Most of you probably heard of the Gigapxl Project. They produce digital images with a stunning resolution of several thousand Megapixels. The Gigapxl Project uses custom-built large format cameras, a technique quite unavailable for most people.
xRez, on the other hand, specialized on producing gigapixel images without special equipment. Instead of taking one gigantic image, they shoot hundreds of pictures with cameras, no different than those that are used in photo journalism. Then, they stitch those hundreds of shots together to get a gigapixel picture.
At their website, there is a nice gallery of some panoramas they have produced. Interestingly, those panoramas are shown as a Google Maps application, so you can pan and zoom as you like. Fun.
xRez also uses their high resolution footage to create special effects. There are several demo videos available.