"A faceted classification is like a controlled vocabulary of "concepts and their associated labels that can be
used, in association with a notation and a prescribed citation order, to synthesize the classes that will populate the classification scheme" The link is a whole chapter on different classification schemes.
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.