I’m a fan of autostitch, and use it quite a lot to make panoramic shots. Microsoft Labs has hit on a great idea that takes this to a new level: Photosynth. Of course, the name tells you nothing. The product sorts through a bunch of photos, and figures out their relationships with each other. It then takes all these photos and places them in a 3d world, trying to replicate the exact way they were taken. This is sort of backwards from the GPS & direction EXIF information that will be coming with cameras in a few years, but it is still very cool. When it is done, you can fly through the 3d world of photos, enlarging some, or taking a virtual tour.
PS – Sony just put out a GPS tracker. It logs where you were and the time, then you can sync that up with your photos after the fact.