People are always aiming for records. While the digital photo industry is all about bigger sensors (despite the fact that it would be better for the actual user to have more sensitivity now that we reached about 5 mega-pixel level), some think ahead and want to create really big images.
In 2003, Max Lyons has stitched 196 images taken of Bryce Canyon in Bryce Canyon National Park in Utah, to create a magestic 1.09 giga-pixel picture.
All tools he used are pretty standard, but it takes some real will power to get to that level.