Darkness,
When I get back from a holiday I can never remember where I took most of my photographs. I'm not organized enough to take notes. The Garmin GPS devices will take tracks, but they start to overwrite after a day or so, and I do not carry a laptop around with me, so for a week away, the tracks are useless.
So I bought one of
these
Waterproof, and I can drop the tracking rate to 90 seconds, which should be good for a 3 week trip.
GPSBABEL or Garmin Mapsource will download the tracks.
Sync the camara clock, and the Garmin clock, and I know exactly where and when the photo's were taken, once I get round to downloading the tracks and the photos. I also get the speed and altitude.
With a bit of twiddling in Google Earth, I can link tracks and photos.
Steve