Speaking of Danny, he’s pointed to two terrific RDF resources:
The first is ActiveRDF allowing access to RDF data from Ruby-on-Rails. This one I can’t wait to try.
The RDFRoom — using RDF to create a virtual 3D room. Appropriate after my last post.
I wonder how OPML could be used to create a 3D room? It would probably consist of one, looong, staircase.