The concept of GeoTagging - adding metadata to a digital camera photo that includes that latitude and longitude so you know exactly where a photo was taken - is pretty useful and neat. However, getting the GPS data merged into the files requires special equipment and takes a bit of time.
I found out that Eye-Fi, makers of the WiFi SD card, now have a service that for $15/year, will automatically GeoTag photos. It does so by looking for nearby WiFi networks that are mapped by Skyhook wireless. I was a bit doubtful that this would work, but was pleasantly surprised by the results. This isn’t “real” GPS - no satellites are involved - only WiFi, but the location data was remarkable accurate; certainly “good enough” for casual photo taking.
The Eye-Fi “Explore” includes unlimited GeoTagging; other models require the $15/year service plan.