When you have a corporate or brand website as the main dish of your online marketing campaign, then it is a good idea to add a corporate / brand blog as your side dish. This blog could help you boost traffic. It can contain anything but maybe the best topic is about your own expertise.
If you update it regularly with good content, people will always comeback to read it. If you do it really good, people will link it.
The blog can be inside your website or using different domain. Both have their own strength. If you use same domain, it can increase you search result rank with keyword optimization. The regularly updated content will surely support SEO.
If you make it in different domain, you will have broader choice of traffic to talk about, plus you could always put link to the main website. Increasing your PageRank.