The LUF service is basically a RESTful API that permits publishing and retrieving user-generated feedback in the forms of ratings, comments and tags. This information is semantically stored in an RDF repository following the Review Vocabulary and the Tag Ontology (as in revyu.com), and exposed as Linked Data. In SOA4All, we used it mainly interconnected with other components of the SOA4All Studio to provide feedback on services.
More technical stuff can be found at http://soa4all.isoco.net/
We opensourced the code into GitHub, and we also used it in the Web N+1 project, for ratings on Linked Data from El Viajero. Additionally, we also processed some ratings from the Linked Movie Data Base, and finally we also submitted the dataset to CKAN (now “the data hub”)…
Ok, it will be difficult to find our bubble in there, but if you open the diagram, a hint is that we’re just at the Northern end.