There is a 13-volume series of Business Plans Handbooks within the Gale Virtual Reference Library. Click on the "View publications" link for Business to see the individual volumes. (Rutgers-restricted access)
There are also many Free Sample Business Plans offered by Palo Alto Software.
Advice on managing your business, from "Thinking about Starting" to "Getting Out," is available from the U.S. Small Business Administration's Starting & Managing a Business.
The Financing Your Business Guide will lead you to many other print and online resources, including several directories of venture capital and angel firms.