Many, many businesses now use blogs for external and internal communication. From Fortune 500 companies, to tiny one-person operations, blogs help businesses develop highly communicative relationships with the community around them. Stonyfield Farms Dairy, has 5 different blogs to communicate with their customers. Signs Never Sleep is a fantastic blog for a little sign making company to demonstrate its works in progress.
Social movement participants, academics and people seeking to highlight their interests and brilliance to potential employers are all using blogs as well.
This site is a blog, hosted on Google's free service Blogger . There are many different free and paid blog hosting services and many, many different ways to use blogs.
I can help with blog set-up, strategy and promotion. It's lots of fun.