The number one benefit to starting a blog for your website is providing search engines like Google new and relevant content to crawl each time they visit your site. All the major search sites have updated their algorithms to give websites with content that is directly applicable to the site a higher rank than those that provide little site specific content.
Be a leader in your industry and engage your users with your expertise, new content and products. By integrating social media with your blog, you can instantly expand your message to more than just your websites audience. Social channels and commenting will allow you to talk with your audience, as opposed to at them.