I read a great ReadWriteWeb article the other day with an interesting recommendation for a Business Model for Twitter.  The article explains how Twitter could sell promotions for a 'Recommended Person to Follow' to brands looking to add more followers.

Although I am a bit skeptical about the size of the market for this specific offering - I do think it's a step  in the right direction.  What is important about this approach (and that the article failed to mention) is that it would pair perfectly with Twitter Search - and serve as Twitter's version of AdSense: A perfectly optimized marketplace connecting Users looking for information & people to follow and brands looking to market their expertise & gain followers.  By focusing on Search,  Twitter has an opportunity to compete Google and Yahoo for search advertising dollars by dominating the 'Real Time Web' - the one thing the big guys actually aren't that good at.  Finally Twitter also has a unique opportunity to revolutionize this search space by establishing a PageRank for people, escalating/highlighting the search results of 'authoritative' users based on quantity and quality of the people following them - much like Google's PageRank does for websites.

As John Battelle noted the other day - Google and Yahoo realize this last point as much as anyone, which is why they have yet to directly integrate Twitter Search results into their on Search Engine Results Pages - and therefore validating Twitter as the central nervous system of the real time internet.