Derrick Tennant

This plugin adds attribution inputs to the media uploader and “edit media” page. It includes a number of creative common license, public domain, fair use, and standard copyright. It will link back to the author’s page at either the end of a post/page and/or the attachment page. If you have a Flickr API key, it can automatically pull information for Flickr images (copyright, author name, title, description, etc). 
It adds a few settings to the Media settings page. You can add a Flickr API key, or display Creative Common logos for their respective licenses.
To style the attributions, I’ve added these CSS classes:
<ul>
<li>a2k-container – A div that contains all of the other elements</li>
<li>a2k-sources – Contains the text “Source:” or “Sources:” depending on the context</li>
<li>a2k-title – The attachment title</li>
<li>a2k-copyright – The copyright information. It may or may not contain an img tag, depending on your settings</li>
<li>a2k-author – The author information. If an author link is provded, it will contain an a tag.</li>
</ul>
Feel free to contact me, emrikol@gmail.com, if you have any problems or questions.

Attributron 2000

Easily add attribution to attachments and have them displayed on your posts.

Haldaug

This plugin adds support for providing licensing information for images uploaded in the media library. The user can input the Creative Commons licensing information in custom fields in the media post. The licensing information is displayed underneath the image in the wp-caption element.
<h4>Credits</h4>
This plugin is based on the code given in the tutorial ‘How to Add Custom Fields to Attachments’ by Guillaume Voisin: <a href="http://wp.tutsplus.com/tutorials/creative-coding/how-to-add-custom-fields-to-attachments/" rel="nofollow ugc">wp.tutsplus.com</a>

Creative Commons Tagger

Adds support for tagging images with creative commons licenses.

Attributron 2000 vs Creative Commons Tagger