Nice as these are, I can't help feeling that they actually help make my point about the current state of RDF in biodiversity informatics. The only responses to my challenge have been to use geography, where the shared coordinate system (latitude and longitude) facilitates integration. Having geographic coordinates means we don't need to have shared identifiers to do something useful, and I think it's no accident that GBIF is one of the most important resources we have. Geography is also the easiest way to integrate across other fields (e.g., climate).
But what of the other dimensions? What I'm really after are links across datasets that enable us to make new inferences, or address interesting questions. The challenge is still there...