Subject-based Advertising

John Battelle has a description of the workings of IndustryBrains. IndustryBrains offers a subject-based advertising network. The question s however how you arrive at those subjects. Normally these subjects are taken from the context of a web-page. This is however not accurate enough. IndustryBrains makes this better by assigning the subjects themselves (I guess). The targeting of an ad is therefor much more accurate and has more value.