A blog provides your business with a ‘voice’; an opportunity to give your company a personality which customers will warm to, and want to be associated with.  A blog should never be a 'flog' - it is a marketing tool designed to establish expertise, increase familiarity with your business, and interest customers and prospects alike.  They help to build a positive and powerful reputation, and to drive more traffic to your website, giving you a further opportunity to up/cross-sell.  Most importantly, a blog needs to be something that your customers will want to read – keep it light, and don’t be afraid to incorporate some humour, if the subject allows.