In my youth I was fascinated with archaeology. Still am, actually. I have, in my time, dragged my parents and friends through every Egyptian gallery I could find and museums remain some of my favorite places to visit. There's just something fascinating about fragile things, hundreds or thousands of years old, that have survived war, natural disasters, and human nature. It's not surprising that archaeologists have adopted a variety of sensor technologies to help them to detect and map ancient settlements and sites but I hadn't realized quite how much they could achieve with these methods.
That is, I didn't know until I read the article "Mapping Ancient Civilization, In a Matter of Days" in the NY Times about the use of a new, more advanced type of LIDAR to map ancient Mayan settlements through a thick jungle canopy. The Airborne Laser Terrain Mapper can be used for far more than archeological surveying and mapping, but is a powerful tool for archaeologists. Actually, if you're interested in learning more about its application, check out the publications from the National Center for Airborne Laser Mapping. LIDAR doesn't have to be airborne, either; earthbound systems exist and have been used to digitize features of ruins and, in a very ambitious project, to document and produce 3D scans of Rome's catacombs.
NASA's Marshall Space Flight Center Earth Science Office maintains a program devoted to applying remote sensing technologies to archaeology and here you can learn the various types of remote sensing used as well as view some of the results from archaeological sites. If you're curious how magnetometers can be used to tease out archaeological features, there's a lovely case study at the Gem Systems Web site. And if you want to ogle some truly spectacular satellite images, I'd advise a visit to the Satellite Imaging Corp. Web site and its gallery of ancient observatories.
This panoply of tools is enabling archaeologists to examine ancient sites in ways that weren't previously possible. Not that they'll be tossing out their machetes any time soon, since any kind of remote mapping still needs to be confirmed by ground-based measurements. But the richness of the data that is now available to them can only help them to tease out our history.