A Free yet feature rich metadata plugin that can optimize your web site for more efficient indexing and easier sharing of your content.
Allows a user to add dublin core metadata (of their choice) to a wordpress post.
Implements some Dublin Core metadata elements for WordPress posts.
wp-RDFa brings the semantic Web to WordPress
It allows to manage a publication repository and exposes metadata in order to be indexed by Google Scholar
Inserts OWMS metadata as meta tags into all post types. Provides options screen in admin area for setting default values.