Right, you don't count on Digg to generate conversions or repeat views or anything like that, because almost by definition, they're the sort of people that flit from news story to news story and never go deep into anything.
However, they're also the type of people that like to tell people about their great discoveries on Digg. The Mavens, on Gladwell's Tipping Point adoption curve. They don't spend money, and promptly lose interest a day later, but one of the people they tell may start using your product or telling people.
When we first launched Diffle, we put a game up on Digg to gauge response. We got about 1200 visits off that. Of those, 6 came back later. But one of those 6 must've told their friends, because 6 months later, we were back up at about 1200 visits/month with no additional publicity. (And there it stayed because the site sucked, but that's another issue.)
