I have recently started geo-tagging some of my pictures that I put on Flickr. It is fun to browse your neighborhood looking for pictures of familiar places and unusual things. But besides the emerging use of geotagging for restaurant and home searches, I think it has value to those great-great-great grandchildren of ours that will choose to be scientists.
This week my wife and I found a creepy spider in our apartment. We took several pictures of it before we got rid of it and it occurred to me that if other people see the same spider species in their houses and take geo-tagged pictures, this data could provide really accurate estimates of species range dynamics that would be potentially easy to data-mine out of the user-generated web.
Flickr is also a great community for rating pictures so peer-review of the pictures is also possible.
So when I tag pictures that might have scientific value in the future I am going to try to put myself in the shoes of these great future scientists and add the tags that I would wish to have for research.