In his recent blog post entitled How to use Citation Typing Ontology (CiTO) in your blog posts , Martin Fenner describes a plug-in for WordPress he has created that makes it easy to add citation typing into your blog post, using a sub-set of the CiTO (Citation Typing Ontology) relationships presented in a convenient drop-down menu.
Jodi Schneider of DERI has posted on her blog at http://jodischneider.com/blog/2010/10/18/cito-in-the-wild/ a most helpful description of how to employ CiTO properties characterizing bibliographic citations as tags for references in CiteULike. Thanks, Jodi!
Egon Willighagen, at Uppsala University, has pioneered the use of object properties from CiTO, the Citation Typing Ontology, to characterize bibliographic citations in CiteULike, the free service for managing and discovering scholarly references. Indeed, it was his use case that persuaded me of the need to generalize CiTO to include indirect citations.