The best way is on your site to setup a php script that will check where your visitor came from. If they came from digg then you either ask them to digg you or do it for them. If you send them to digg from your site inside of a tunnel you can easily find out where and how to digg for them.

Other than that, its about natural placement. I would suggest a few tactics. One, racisim. I know, its bad. I am not saying support it I'm saying write about it. People love that crap.

Keep it simple. Your dealing with smart people and really dumb people, and hardly any in between so either target the dumb ones or the smart ones. There is no magic button though. And in the next 12 months it will get even more difficult as blogging is accepted into its own search engine rankings and so on. So spam stuff is going out the door. I'm glad. I stills ay, even as a blackhatter, I kick the teeth out of any cmpetitor who uses machine generated results. Why? I take the time to add my own flavor and influence and people are at ease with typos and mistakes they would generally make.

Just my opinion.