PhotoSync keeps your Flickr account up to date for you. It is a desktop application that automatically synchronizes the photos between your computer and your Flickr account. It monitors a directory on your computer any changes you make in this directory will automatically be reflected on Flickr. Similarly, any changes that you make to your Flickr photos will be synchronized back to your local computer.
This app has a very specific purpose and it performs exactly as described. It's great to be able to organize and update my Flickr photos. PhotoSync is very reasonably priced considering the benefits it provides. If you try it, I predict you'll buy it.
PhotoSync will be even better when it can handle sub-folders. The developers are working on this feature. It is still well worth the price just as it is now.