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.

mitcho (Michael Yoshitaka Erlewine)

bmellor

The License plugin gives authors the ability to mark their content with a <a href="http://creativecommons.org/" rel="nofollow ugc">Creative Commons</a> license and to display the license along with the content. With Creative Commons licenses, you keep your copyright but share your creativity. By default, the plugin will display a license in the footer of your theme. The license plugin is also a widget, and can be dragged to any widget area. This will supress display of the license in the theme footer and display it instead in the widget area.
The site default license is the Creative Commons <a href="http://creativecommons.org/licenses/by-nc-sa/2.0/" rel="nofollow ugc">Attribution-NonCommercial-ShareAlike (CC BY-NC-SA)</a> license. Authors can set their own default license using the license settings provided under Personal Options on the edit profile page. The license can also be set for each individual post using the setting provided in the Publish box while creating a new post.
Authors can choose how they would like their attribution to be displayed on the site. The author can attribute the work to their display name or their nickname as defined in their profile options. Alternatively, the author can attribute the work to the site as defined in the General Settings of the site.
This plugin is a component of the <a href="http://ecs.mit.edu" rel="nofollow ugc">MIT Educational Collaboration Space</a> project.

License

The license plugin gives authors the ability to mark their content with a Creative Commons license and to display the license along with the content.

Attributron 2000 vs License