Eric Enge has wrote very good article about success on digg. Some of details he presents are maybe not true anymore, because DIGG evolves and changes internal algorithms. However some facts are really interesting.
As he says, stories that where able to reach the digg home page receive an average of 129 links, and more than 10,000 visitors in an hour. Some stories have brought even more than 1,000 links and 100,000 visitors. This shows how important DIGG is and why there are so many legend and so much attention from SEOs. So it has happened many times that stories which have made the home page, have brought the server of the story site can't handle the traffic load. This is well known phenomena called as the "Digg Effect".
Of cause the quality of this kind of visitors is "bad". Don't expect that they will by your products and click Ads. Do not expect big growth in comments, DIGG users often comment regarding a site on digg itself instead of on the dugg website. Digg users comes to see only that what they would inspect in the story description on DIGG itself.
I don't wanna be a Digger
So after reading several articles about how to success on DIGG i realized that it would take very very very much time. So as every body know time is money, but moreover time is life! In my opinion the truly success on DIGG starting from null will deserve much to much time in comparison to the revenue.
Personally I don't have much time and will not spend it to fullish site like DIGG, voting for silly topics of US teenagers :).
Update 2013 Digg is dead... The ruler's underestimated the community. Learn this lesson!