Flickrstream - order your photos by taken date
Update: Flickr has locked the ability to have an upload date earlier than your account creation date. This means that all your photos with a taken date ealier than your account creation one won't be sort out.
A simple and cool application using the Flickr API to order your photos (main photostream) by taken date instead of upload date. This way they are displayed chronologically.
You can restrict the batch by set, tags, or dates.
Bonus: if you want to process your photos with your own API key, you can download the application and upload it to your own webserver.
Note that you can't undo it since the upload date will be lost after applying the modification.