Yes it can be very effective for some people, depends on how many directories you submit to and their quality and plus the popularity and quality of your article.
Its the golden formula to drive traffic to your site . This formula can never fail . You wont get too much traffic , but traffic will be regular.
We run www.uronlinebiz.com which is an eZine. We put it up on the eZine directory which seems to help. We have a pretty unique concept with our mag which people oftern over look and miss our unbeatable product prices. We used to have it so there was only a VIP account but resently made a free one given away all the articles we have and making the VIP account for people who are serious about making their own business. Our VIP account is loaded with web master freebies and competative prices on auto responders. In fact i would say we have the cheapest auto responder in the world there. and the VIP account is only 1.99 EUR so we hope the traffic wakes up to this deal.
Writing articles that are related to your website and then including a link back to your site in the Authors Bio Box can have a huges impact on your traffic as well as your websites placement in the Serp's Tip: If you are writing several article it is wise to vary the anchor text as well as linking to internal pages of your site This is a much more natural linking structure in the eyes of the search engines
I have used it a few times the traffic is not that high but I submitted to my target audience and made a few sales it all depends on the ezine itself if it has good targeted people related to your site it can be a good way of advertising.
I would like some more feedback on this. I just started looking into this seriously today. For those who are confused, the topic is eZine advertising not article writing.