geotagging
last year, I posted photos of Barcelona on flickr.
Quickly, somebody added geographical coordinates to the photo as tags.
This gave me an answer to a question that wander in my head from time to time:
What's a portable GPS is useful for?
I was in Barcelona last week and I've posted photos I took there.
I've geo-tagged them myself, but I still don't have a GPS.
I just use Google Earth and it's quite accurate.
And this is not news as I later found these related links on flickr: