Hitwise Blog published web traffic analyses of search engines, social networks, and news sites, based on the company's audience measurement data.
HN links it for web traffic data, such as the demographic differences between Yahoo and Google audiences.
As an ex-Yahoo (I quit this week), I can tell you our demographic in two words: flyover country.
Here's a demographic study on Google vs. Yahoo from 2 years ago:
http://weblogs.hitwise.com/us-heather-hopkins/2008/02/yahoo_search_draws_younger_aud.html
Google's big groups: affluent suburbia, upscale America, rich small towns. In short: you, probably.
Yahoo's big groups: struggling societies, blue-collar backbone, remote America. In short: middle America (and also poorer urban folks).
Within Yahoo, the general consensus is that our biggest market is middle-aged housewives from the midwest. This is a big group, although as the study points out we actually trend younger than Google -- this is because our media properties, likes games, sports, and IM, attract teenagers, a market Google doesn't really serve.
While a certain amount of traffic is driven through partnerships, it's nowhere near big enough to account for Yahoo's enormous volume. Although they're not new or cool, properties like the Yahoo.com frontpage, Yahoo News (bigger than CNN and the NYTimes combined), Sports (bigger than ESPN), Finance (by far the biggest) and Mail (40% of the market) absolutely dominate their respective categories and, despite the general perception of Yahoo as a company in decline, are mostly holding steady or growing slowly in terms of audience.
The selection bias amongst tech professionals in their perception of Yahoo is a huge barrier to Yahoo's hiring, acquisition, and new tech…
some further food for thought:
http://weblogs.hitwise.com/us-heather-hopkins/2008/02/yahoo_search_draws_younger_aud.html
random blog with some thoughts:
http://www.zephoria.org/thoughts/archives/2008/02/16/who_clicks_on_a_1.html