A few years ago, I did a three week photo trip through the Pacific Northwest of the USA. Upon arriving home, I had the film developed immediately, but found great difficulty in identifying locations. I am planning considerable travel over the next few years, and want to avoid the same problem. I did a ten day photo trip through the Alberta Red Deer River Badlands and the mountain parks in August as a shakedown. Finding information through Google was not at all easy. Most GPS makers do not even mention geotagging, and there seemed to be very little general info. My D300 and D700 both have inputs for GPS units, via cables. The manual is not rich in information. Since I was shooting with both bodies, I really did not want to have to use two units and be burdened by cables that would tangle and get caught in stuff. At Photokina, Nikon announced a GPS unit that would mount in the hot-shoe, cutting down a bit on the clutter. There has been no mention of it since. JOBO has been announcing a similar unit at trade shows for the last couple of years, but I have yet to see it on the shelf. There are a few other variations, but in many cases they look like hacks from small companies and reviews were not particularly positive. Sony has a small track recorder, that I believe now will work with any camera, but initially, it was strictly for Sony cameras. It is very basic. I learned that some GPS units can be set to record a track of wherever one goes, and that there is software that will match the time on each image to the time the GPS has recorded on the track, thus giving you the coordinates. The great advantage of this approach is that one GPS unit would serve both cameras. All that was needed was to set the camera's clocks to match the GPS. I went with this approach and it worked flawlessly. I bought a hand-held unit and mostly carried it in a small waist pack. For software, I downloaded Pro Photo Tools from the Microsoft web-site. It is free for download and worked easily and perfectly, embedding coordinates into EXIF data fields. It also places the location of each shot on a map, and the program even goes so far as to give street addresses where applicable. Once saved, the data will show up in many programs including Adobe Bridge, ACDSee Pro2.5 and IrfanView. Open the image in IrfanView and click a button, and Google Earth will open with a pin showing the location of the shot. Very nice. In all, I returned with 36GB of image files, and I can identify the spot from which each one was taken. While Pro Photo Tools worked great, I see that Picasa and JetPhoto - also free - include geotagging. Perhaps it is finally coming of age. I might add that while tracking was the main reason for buying this unit, it proved to be much more useful. I was able to use the software to load in a map of the area where we would be traveling, and actually map out the whole trip, with slack for side trips. This was then loaded into the GPS unit. It both showed maps where we were going along with present location, but also gave narrative instructions. It got us back on course when we took a wrong turn a couple of times. It also identified locations for fuel and lodging.