I had the opportunity to take a trip last year which covered the better part of Ireland.  While there, we had two cameras: a Nikon D70 DSLR and  a Sony DSC-N2.  More importantly though, I had a Sony GPS-CS1 geologger.  This little device locks onto GPS signals and records your location every 15 seconds in standard NMEA format to internal flash memory.  If you take the time to synchronize the internal clocks in your camera to GPS before you go shooting, afterwards you can correlate the time stamps in your photos with the position recorded by the device.  I use software by RoboGeo to do this, although Sony includes some basic software with the device.

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