While comparing the layouts of the websites of The New York Times and the Daily Mail, John Pavlus coins a pithy description of what websites are for:
In pure machine-interface terms, The Daily Mail is "for" getting visitors to click a lot (to serve ad impressions), not read a lot. So the Daily Mail provides scads of affordances for clicking, often at the expense of those for reading. And it works like gangbusters (for now, anyway). That is all a technological interface has to do: work.
I'm still hoping that a free-to-use model emerges that doesn't depend on advertising, but so far the only example I can think of are cosmetic microtransactions for free-to-play video games.