How does social bookmarking sites make money?

Hi,

As the title says how does social bookmarking sites make money. Sites like diigo, bizsugar etc.

Their content is duplicate and still panda doesn't penalise these domains.

Please share ideas for both these questions.

Mostly from advertising revenue or selling the data to data mining companies that aggregate data and develop statistics about certain things.

Through social bookmarking sites, people can save their favorite sites and share them with the world, friends or keep them private.This is a very good way to start off any website you have that you hope to make money with.

Having high PR Social Bookmarking sites linked to your site will improve your site's PR

Social bookmarking is really a lot like ordinary bookmarking in a way.In addition, you "tag" the social social bookmarks together with key phrases. This helps other folks to locate them as they can perform a search depending on the keywords and phrases, or even when the hunt for that keyword they may discover your save.
You may make money straight with social bookmarking via one or more website. Reveal A web link can be a revenue discussing social bookmark submitting site where you can make money through the Let's consider google adsense program.

Something tells me out of all the people who answered OP only the_demon actually read the question posed.