What's a Digg worth?
Here's a comparison of two events from Digg.com and how they translated into actual website visitors.
The first is a front page story on Digg.com - in this case, a survey I put up in August 2007. The story, "What do Digg users think of the world?." received 5045 diggs.

The story linked to a ten question survey, which was completed by 45,000 people. I don't have stats on the total number of visitors that didn't complete the survey, unfortunately. The survey did not require users to answer every question, so the completion rate of 100% includes anyone who gave even one answer out of ten.
In this case, a front page story on Digg.com in mid-2007 equated to about 9 completed surveys per digg - and an unknown number of visits without user action.

The second is a comment on another person's story on Digg. This story was about a new concept car from Toyota, and the story itself had 962 diggs. My comment, a response to another person's comment (which itself had 124 diggs), had a total of 3 diggs.

In that day, there were 104 unique visitors to the linked story (Tokyo Motor Show).


There are three ways to interpret this:
A comment on a front page Digg story translates to either:
One visit for every 9 diggs (based on the popularity of the story)
One visit for every one comment digg (based on the parent comment)
or
35 visits for every comment digg (based on the popularity of the comment itself).