If you are known at Twitter for sharing your Flickr photos but you are on the lookout for a tool to make that easy, then Flick.to.Twitt will come in handy. The startup lets you upload photos to Flickr and while that is done, each of the upload is announced on Twitter too. There is no need to register or download anything, simply use your Twitter and Flickr user ids and the rest is as easy as uploading photos on Flickr and posting at Twitter.
