There isnt. Why would a lot of diggs help you with SEO? It will help with traffic, but will only help with SEO if other people like your article and link to it from their own site.
There are so many ways to work with Search Engine Optimization and YES!, Using Digg to gain traffic can be a good one. If you have a Google Analytic's account, then it should notice the "Bounce Rate"... The longer that people stay on your page... The better. Keep some good and updated content and keep them coming back. Just hope that they link to your site from there website and some links that have been DIGGED; can earn a good PR over a long time. ~ Mike
the more diggs you have for your post in digg, your link will be shown in all the diggers profiles and that is beneficial for your post.