Kubrickr: Interactive Flickr/WP Design Tool
However, what makes it so cool is that it has a virtual overlay the same size as the default header image for Kubrick (the default WordPress theme) that allows one to slice out the portion of the selected image that one wishes to use for a header, and then generates the newly-cropped image on the fly for downloading.
Very cool and simple and clean -- Kubrickr even filters out images that are not up for sharing by checking the licence before it displays an image in its search results.
Frank