If you want to start using a GPS device to Geotag your pictures, (that is insert your lattitude and longitude (and height) into them for displaying on a map), there's quite a few different options to look at.
I've knocked together a quick video looking at three different models, that Geotag your images, but all in a slightly different way: The Amod AGL3080, The ATP Picture Tracker, and the Qstarz Platinum.
Until I got my hands on, and used the Qstarz GPS Travel Recorder, I would have been happy enough with the Amod, or the ATP if it was more reliable.
The Qstarz BT-Q1000P just does so much more. If you put aside the fact that it can also turn your smart-phone or Pocket PC into a GPS Sat Nav, the way the included software makes it incredibly easy to tag your pictures accurately, then make Google Earth .kmz files, makes it the winner for me.
To check out what a Google Earth kmz file, which includes track and pictures, looks like, have a look at my Photowalk in 100 Acres Wood.
My advice? If Geotagging your images is important to you, and more and more services are using GPS Tags, grab the Qstarz - it's always with me when I go out and take photos.