Digg is awesome for traffic if you can get about 50 or so diggs in the first hour... (usually that will put you on the front page) then you will get Tons of traffic... not necessarily 'targeted traffic' But the nice thing is you'll generally speaking have a few others blog about your article... and or link to it from one of their pages...
So yeah it's good for
SEO but it's not nearly as game-able as it once was....
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