A blogger enlisted a few Twitterers to post a link to one of his blog posts and see how traffic improved. The results of his experiment are here.
This is an idea Ive always wanted to try. I figured that it would work, but it is hard to tell to what degree. The problem with this blogger's experiment is that he simply said that the hits on his website doubled. Did they double from 5-10 people or 5k to 10k? It is a vague term. I wish he would have clarified that, but it is an interesting experiment never the less.