I am asked from time to time whether or not I think it is important for a client to Blog or not to blog.  Here are my thoughts on the subject:

Advantages:

1. Blogging is a great way to add current hot topics to your website (this post is a good example!).
2. Blogging is a great way to add lots of search engine friendly content to your website.
3. For certain industries (i.e. Food prep, coupons, computers, seo, etc.), consistent blogging can help grow a loyal following and brand yourself fairly quickly (yet with a lot of effort).

Disadvantages:

1. Time.   The most successful blogs have people dedicated to not only writing lots of blog posts/articles, but also being involved in the blogging community.  All of which takes an enormous amount of time and effort.
2. Low Sales Volume.  For most industries (i.e. local movers, dentists, attorneys, etc.), no matter how much you invest into your blog, the people following blogs are more likely competitors rather than people looking to buy your products or services.
3. I am not much of a writer, nor enjoy writing all that much.  This is a disadvantage for me.

Conclusion:

To Blog or Not to Blog, really depends on your industry.  Are you in an industry where you can develop a loyal following outside of your competitors and brand yourself to people that may buy from you someday?  In a way, anyone might benefit from blogging at least a little.

Perhaps a good rule of thumb is to Blog once per month per employee.  I have one employee (myself), and have found blogging about once per month (or less) is a good fit.  I like to have the ability to add information about current hot topics and who knows, maybe I actually have a following out there.