Does your company Web site have a blog? What do you use it for, what's the ROI?

We've been using a blog for several years now. We add instructions for our existing clients (such as how to use our project management intranet); we inform the masses about our new discoveries in the fast-changing world of Search Engine Optimization and Social Media Marketing; but most importantly, it adds credibility to our potential clients that want to get a more personal, current assessment of our company. Our blog ROI is hard to measure, but since we do custom blog design, and blog marketing services for our clients, my company blog is an essential part of our overall marketing strategy. ~ Frank