we map flickr Blog
What's more, you can add your own places, assuming they refer to a flickr tag.
Not making sense? Check out Google local, flickr and we map flickr (since taken offline).
The issue with putting cities on a map of the world is getting high quality geocoded city names. This is the reasons that, so far, I've only managed to put up some 7 countries. More will follow, however.
On a side note, I stumbled upon a very lovely collection of pictures here and a great flickr implementation here.