I am working on a 'three purpose' task this morning: writing an RDFa parser in Common Lisp. I need this for my new book project (semantic web application programming with AllegroGraph), I need this for one of my own (possibly commercial) projects, and to release as an open source project. I am building this on top of Gary King's CL-HTML-Parser, so Gary did the heavy lifting, and I am just adding the bits that I need.