Currently we have a demonstration search that works by telling AlltheWeb to limit results to pages that link to Creative Commons licenses. While useful, this is far from our vision of a metadata-aware search engine.
The first requirement for a Creative Commons license-aware search engine is that license metadata (RDF embedded in pages) must be indexed. It wouldn't be necessary to index arbitrary RDF initially -- indexing only Creative Commons license metadata would be a good first step along the path to a Semantic Web-enabled search engine. Please read the detail page for further information Add license search to a major commercial search engine.
"Who remixed me?" as the new "Who linked me?" This is along the similar lines as trackbacks for blogs which are used to see who is sampling which blogs. Please see the detail page Source Query.
Improve search support in services like http://flickr.com/creativecommons. This could be done by outside developers in cases where web service api permits. Please see the detail page: CC search for content repositories
You'd have to work at a commercial search engine to tackle the previous challenge. However, an individual or small team could build a search engine exclusively for Creative Commons-licensed content, much as several have been built exclusively for searching blogs. Please see the detail page: Write a custom Creative Commons license-aware search engine.
Add support for Creative Commons licensing to content discovery applications such iRate which help you find interesting media based upon your favorite playlists, friends choices, and what is popular. Please see the detail page: Discovery Tools.