What is the best tool to use to syndicate articles, where, others are likely to re-publish your content and link? Currently, I use isnare, and a few free article directories such as ezinearticles, searchwarp and goarticles.

Is there a good submission tool that will submit the article to the major article directories?

Does anyone find that adding your article to Digg is worth while? I always add to my blog and then of course ping Technorati as well as use pingoat to hit some of the other RSS aggragators.

any thoughts?