Digg traffic is mostly garbage, in my opinion. I have made the front page a few times, on two different sites. In both instances it crashed by site very quickly. However, the traffic was pretty much completely unresponsive to ads. I got like one click per every 10,000 visitors, so basically they crashed my site and burned my bandwidth for nothing.

Maybe if you have an apple fanboy site selling ipod assessories, you may do better, but for the most part, digg is garbage. Maybe if you are running CPM ads and can make the front page consistently, you may like digg traffic, but for most people they are a waste of time.