I've been a member of EzineArticles for a while now, and have quite a range of articles up there. One thing that's really struck me is how the category of the article influences the number of clicks the author bio-box links get.
The articles that have just commentary and opinion get next to no clicks, even when they get a lot of views. Take this article about a media scandal involving supermodel Miranda Kerr. It's been viewed over a thousand times. Yet I have not received even one click from it!
This article about getting paid for writing letters to magazines has only been viewed 175 times, yet I've had 6 clicks from it. That works out to a click-through rate of about 3.5%. Some of my other similar articles have had even less traffic but higher click-through rates.
Clearly, the "how to" guides, and those articles that include lists of tips and techniques about a certain subject get the best results. The reader senses that you can help them somehow, so they are more likely to check out your site to see what other useful insights you're offering.