Found this a set of interesting tools over at Microsoft adCenter Labs. The image above is of their Search Funnels that show queries either preceding or following your keyword in other people's searches. In other words, 194 out of 4,200 searched for "honda" after searching for "vw" first, and 182 searched for "toyota". Could be useful for refining consideration sets. Also check out the tool that predicts commercial intention associated with particular search terms.