Great mix of mapping and photos: Mappr!
The release of the Flickr API
has proved to be very fertile, and now has produced a gem: Mappr
tries to interpret the tags of photos, to place them on the map of the US. Of course this should be immediately extended worldwide! Since you can look up other tags
that are not geography related to create collections, and you should also be able and select the date of the photos, I can already see how you could follow the seasons of blossoming through the continents by looking at the right tags the right time.