I just had another one of those head-slap, “Why-didn’t-I-think-of-it” moments. It came right after I read New York Times columnist David Leonhardt’s latest piece. It’s about Google Trends.

That’s the new product the search engine has put out to make use of all the data it collects. Everytime you do a search, you’re looking for something or otherwise recording an interest in something. The more searches that are done on any word or name, the more likely it will soon become a pretty big thing.

The smart guy who translated this into a usable form was John Battelle, who helped found Wired magazine and The Industry Standard. He called it the “Database of Intentions” and said on his blog that it was “a place holder for the intentions of humankind — a massive database of desires, needs, wants, and likes that can be discovered, subpoenaed, archived, tracked, and exploited to all sorts of ends.”

Leonhardt notes that this data was good at predicting the most recent American Idol winner and the relative strengths of Hilary Rodham Clinton and Al Gore. The former vice president apparently got a big boost from his documentary, “An Inconvenient Truth.”

Google uses this stuff itself but is releasing some of the data for public use. It’s going to be one more thing that will say where the markets are going.