This is a great one for the perennial question of how to make money off of blogs. Rather, actually, it’s an example of how a site with a solid revenue model already — e-commerce — can use blogs to make even more money. (NOTE: this case study from MarketingSherpa will be availabe for free for only a couple of weeks.)

The case study tells of how T-shirtKing.com increased its sales dramatically using a blog. The site was in the habit of writing long essays about the subjects of its t-shirts — for example, biographies on Miles Davis and Albert Einstein — for its email newsletter, which were quite popular with subscribers, but anti-spam filters were taking a toll on the effectiveness of its email program. So, using Movable Type, the site redesigned its site to publish via a blog, and added a blog to its content mix, publishing the essays in that format. The essays and the blog publishing platform worked well to drive more organic search traffic, and played into the site’s affiliate program as well. The results, according to MarketingSherpa, were dramatic:

Site sales tripled during 2003, and have continued strong in 2004. Altogether, blog content helps to bring in about 35% of total site sales — 10% from the email newsletter, 20% from affiliates who often reuse the content, and 5% from Blog traffic itself.
Blog readers are among the traffic most likely to convert to buyers. “Six to eight percent of Blog readers buy something. Once someone finds a Blog entry and reads the whole thing, they are about as qualified as you can get.”

MarketingSherpa: How to Build Your eRetail Business with a Blog (6-8% of Readers Convert to Buyers)