Geotagging images is popular. With some simple software the longitude, latitude and altitude information captured with your images can be plotted in popular mapping applications like Google Earth. The Phottix Geo One GPS unit for Nikon DSLRs gives you the ability to add GPS data to your JPG and RAW files. The Geo One is small and mounts on your camera’s hot shoe or strap.
The good folks are Red Dot Photo put together a neat little video on what the Phottix Geo One can do, and how to process GPS data in Adobe Lightroom 2.
The Phottix Geo One is compatible with Nikon D90, D5000, D3, D300, D700, D200 cameras and is available from Phottix retailers and at the Phottix Online Store.