Photo Crank is as online service that lets you add captions and entertaining graphics to web photos on the fly – you could use this either for fun (like running a caption contest) or for collecting feedback on certain photos.
And there are no licensing issues because the photo stays on the original website.
You can add a line of code to your blog template and readers can then add captions to your photos and images while staying inside the blog. These comments are automatically saved with the photo and others can also read them.
To see all this in action, visit the blog of fake Steve Jobs and wait for this photo to load in the browser. This will particular interest blogs that are about celebrities.