In our tracking projects (GPS/GPRS systems in industrial plants) we leveraged Zoomify technology to process the plant images (usually took from an airplane and the reassembled by post-processing).
Today there is also SilverLight with DeepZoom to achieve the same result but if you're still working with Flash Zoomify it's still the best tool.
A new version (Version 4) has just been release. Take a look here for the main features.
To my colleagues: PLS take a look!
PS: About tracking project, this week has been published a white-paper from my company about a project on Iron & Steel Technology magazine. It's at page 58....