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.

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.

Creative Commons Tagger vs License