Flickr is photo hosting and sharing site that also happens to be one of the best examples to demonstrate that how a good Web 2.0 based online service should be built. It is extremely popular among people that want to privately share private,family photos or want to share their photographic creations with the general public. It is estimated that Flickr now holds over 2 billion photos. Key reason for its popularity is the wealth of useful tools that it provides to its users to upload, manipulate, ...