Blogs can definitely provide additional traffic. However, if your goal is to generate QUALITY traffic then you need to provide value in the blog. Don't just create a junk blog with recycled content and keywords out of context to try to build traffic; that strategy will ultimately fail because you will not be providing value and you will lose trust. If you focus on providing value and helping people, word will spread and you will begin to attract the type of traffic that will have a positive impact on your business. For a great example of a blog that provides value, check out Stephen Pierce's blog at dtalpha.com/talkback. Stephen gets traffic and he gives value.