Lorcan Dempsey's weblog: Classify is a protoype service which provides a snapshot of what class numbers (DDC, LCC, NLM) have been assigned to works in Worldcat.
The records are grouped using the OCLC FRBR Work-Set algorithm resulting in a work-level summary of the class numbers assigned a title. You can retrieve a classification summary by ISBN, ISSN, UPC, OCLC number, or author/title. [About Classify [OCLC]]
He points out the LCC numbers assigned to The Consequences of Modernity by Anthony Giddens