When I started my webhosting company, I didn't know the first thing about running a business. Though both me and my partner managed to keep out of debt, we hadn't managed to make much profit. Que said books. As simplistic and obvious as this may sound, a bet the majority of members here who own a business haven't picked up any kind of book on running a business, or marketing for that matter.
Books are your free help. Why hire an attorney, or a marketing consultant when you can just reed his/her book. There are some things that a pretty flash tutorial won't teach you. Half of the rediculously impossible to answer questions can be read about in a book.
The Wizard of Ads : Turning Words into Magic and Dreamers into Millionaires
by Roy H. Williams
A great marketing book. You have to use your head alittle, but a very insightful book. The best thing about it is it illustrates obvious and simple ideas, but you get a new respect for them, and their importance in business. It's mostly told in anectodes, but a great read. The author is CEO of a major Marketing Firm.
Brand Warfare : 10 Rules for Building the Killer Brand
by David D'Alessandro
A simple to understand book about the importance of brand. The author is CEO of John Hancock financial services, a major brand in its industry. Also told with examples and a few anecdotes.