Steve Johnson has come up with a cool idea, Googleshare.

Search Google for a specific word, and get back the total number of results. Then you search that set for someone's name. Divide the second number by the first, and you get a percentage that shows you how much the person "owns" the word. Call it semantic mindshare. Or lexical penetration. Or whatever.

And guess what, Rael has a Googleshare implementation using Google API to do just that. All you need is your Google API key.