Wired has a short article about topic maps; here’s an excerpt:
Databases and search engines provide instantaneous access to endless information about anyone or anything, but the search results often include as many misses as hits. To generate more-relevant answers, organizations including the federal government are using topic maps to index their data.
Topic maps are smart indices that improve search capabilities by categorizing terms based on their relationships with other things. For example, William Shakespeare is a topic that would be mapped to essays about him, his plays and his famous quotes.
Organizing content with topic maps provides context for words that can have multiple meanings, according to Patrick Durusau, chairman of a topic maps technical committee at OASIS, the Organization for the Advancement of Structured Information Standards.
For example, searching Google for “Franz Ferdinand” mixes results for the alternate rock group and the doomed Austrian archduke for whom the group is named. If topic maps were used to organize the data, the musical and historical links would be separated, Durusau said. “The payoff (of topic maps) from the user standpoint is that you are no longer confronted with everything in the world that is known about the subject,” Durusau said.
A good deal more on this in Steve Pepper, “The Tao of Topic Maps.”