Digg died last summer after they forced a broken update on their users to turn it into a fully-fledged social network and content aggregator, rather than a social news website.
As a result of this, a vast majority of their users packed up and left and the results are clear. Their founder and CEO packed up and left, the vast majority of their users moved their time elsewhere and now one only has to look at the front-page of Digg to see that it is laughably dead. Digg never had any SEO benefit to begin with, now it’s probably counter-productive…
The most popular social news website on the Internet right now, by nearly double the users of Digg, is Reddit. Thankfully, for those who just want to use a fun social news website Reddit is extremely hard to game and those who spam will find their sites ridiculed.