I was browsing ShoeMoney today, and I saw a post about a new (or maybe just newer) plugin called Increase Sociability. I had seen it in action before on the front end of a different website, but didn't know that was what I was seeing.
Basically, the idea is to plop a special line of text at the top of your blog post when a user comes to your site through Digg, Stumble, etc. The plugin knows when people came to your site from one of the social voting sites, and it knows which one. It then, for example, will remind the Digg user to digg your post.
However, users that just browse your site the good old fashioned way won't see anything.
The idea is to give the reader just a little reminder to give you a vote. As a result, you should get more social votes.
So, I'm going to test it on a few other sites and see how it goes.