Article writing is one of the MOST effective free advertising methods for bringing high volume, targeted traffic to your website. It's viral and can lead to many unexpected sources of free public relations for your business.
Plus the back links to your website address in your author bio, will boost your website's search ranking on Google, Yahoo, MSN, etc... very quickly.
Here's a list of 92 article submission sites that I've personally used in the past.
To my knowlege, most of these links should work. But since I haven't had to worry about them for around six months, I haven't tested them recently. Still I'm sure someone will be able to make use of them.