FindOnFlickr

This is just an Automator app that looks up the image file you drag to it on Flickr. It does this by assuming the file was downloaded from Flickr, splitting it on the underscore character, and taking the first part of that split result and using it as an ID in the URL ““. If the file did, indeed, come from Flickr, this URL should lead you back to the Flickr page for the image.