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.

CodeAndReload

This plugin provides the ability to tag media in the media library as having a Creative Commons (CC) license. 
The license shows up on the attachment page and is optimized for search engines (SEO) using RDFa metadata. 
It optionally extends the search form to allow searches for CC-tagged media. It can display a text link 
to the license, an image link to the license, or both.
<h3>Support</h3>
Technical support for this plugin will be provided via the WordPress plugin forum. Additional support may be 
available at <a href="http://www.codeandreload.com/wp-plugins/creative-commons-tagger/" title="Creative Commons Media
Tagger at Code and Reload">plugin’s homepage</a>.

Creative Commons Media Tagger

Allows tagging of media as having a Creative Commons license. License info shows as link and/or image and is searchable. Search engine optimized.

Attributron 2000 vs Creative Commons Media Tagger