flick.to.twitt is a service that lets you post a photo to your Flickr account and automatically announce it on your Twitter account.
It was developed by Marco Almeida (@Wonderm00n), project-manager at a Portugal based web company called Webdados for personal use, and then decided to open it publicly.
The main reason this tools was developed was because tools like Twitpic, MobyPicture, Visual Twitter, Greetter, FileSocial, ScreenTweet, Twi5, Twi.tt, TweetPhoto, Pikchur, yfrog, piktor and so many others are great but if the user already has a Flickr account, their photos are now spreaded in several services. This enables you to use Flickr as a photo sharing option for Twitter and keep your pictures all on the same place.
So with flick.to.twitt you can tweet your Flickr in a blink of an eye!