Nice short article from PC Magazine that outlines a few reasons for small businesses to have a blog.
IMHO, article is a bit simplistic for the publication’s audience, but helpful nonetheless.
The #1 reason for me for a small business to have a blog is to increase online visibility and move in the Google search results. If you type “Josh Morgan” into Google, this blog comes up as the fourth result. It was #1 until a guy with the same name started running for office in Canada. Those pesky Canadians!
#2 reason is to demonstrate your industry knowledge/involvement. Show prospective customers that you know what you’re talking about, which saves some time in pitches as they may already know a bit about your take/attitude on specific issues.