LibraryFilter: How do I look up a book's "category"? [more inside]
posted by ObscureReferenceMan on Sep 11, 2008 - 10 answers

Ontology Filter: Give me a name for a category of things that I'm using in a system. [more inside]
posted by Deathalicious on Nov 12, 2006 - 15 answers

Photo categorization software with user defined tags. [more inside]
posted by cm on Nov 27, 2005 - 9 answers