In biology, the interest in RDF & related technology is very high. People want both less parsing and custom code to integrate data, and more advanced queries. RDF is already providing the former; for example, UniProtKB, one of the biggest biomedical resources, are offering their data in RDF. For advanced querying we're not quite there yet, as performance and availability of good RDF data and OWL ontologies is still a bit lacking. But it's starting, check out BioGateway for an example of what can be done.
In that light, the fruits of these technologies are not individual killer apps, but all the accumulated time savings for researchers who can explore the data instead of writing ad hoc scripts and setting up temporary SQL databases and all this plumbing.