One crucial function they perform is the formulation of business plans. This plan is based on the information provided by the client coupled with the vast wealth of knowledge and research a business plan consultant has.
Small business consultants are very much on top of their game. They compile industry reports relating to the business, conduct feasibility studies, as well as studies relating to potential customers.
Internet Public Library - The Census Data and Demographics (ipl.org)/: An especially useful site that has links to information about countries other than the U.S.
James J. Hill Reference Library (jjhill.org): One of the nation's premier business libraries to bring you FREE and affordably priced tools and resources you can use to create a better business plan based on relevant and credible data.