Why a Business Blog?
There are two types of business blog, one to support your existing business and a standalone blog to generate income via affiliate links such as Adsense or selling advertising space on your blog. I am possibly oversimplifying things here but I like to keep things simple 
For an existing business where you sell products or services via a sales website, a blog is an ideal supplement since you can drive more targeted visitor traffic to your sales pages and build a relationship with your customers. They get to know the personality behind the business and not only see a sales pitch.
Blogs allow your customers or potential customers to ask questions, post their testimonials and interact with you. They will feel that there is a caring individual that is accessible and open.
You can easily announce news of new products and tips on how to use your products. Encourage customers to post comments about their experiences of your products and services.
The search engines love blogs since the information is often fresh and upto date unlike many old static web sites. So search engine spiders will tend to regularly visit your blog hunting for new content. Feeds on your blog allow people to subscribe to your topic posts with feed readers rather than needing an email subscription.
Blogs allow you to do social networking to find related bloggers and distribute visitor traffic amongst yourselves to find new subscribers and customers.
For a standalone income generating blog, you want to generate regular fresh content to keep your blog being found in search results and work at increasing visitor traffic. Blogs make it easy to concentrate on publishing topics and networking rather than web design and technical stuff.
New ways to make money blogging are constantly appearing. Examples are selling ad space, hosting sponsored links, hosting affiliate ads or even being paid to blog.
Well I hope this article gave you some idea why you might want a business blog.
p.s. not all free hosts will allow a business/commercial blog since it is against either their philosophy or it would compete with their own advertisements.
