Michael W. McLaughlin, the coauthor of Guerrilla Marketing for Consultants, has written a good overview article on “key factors to consider when building web sites for consultants”:http://www.highrankings.com/issue153.htm#guest.
A lot of the points are equally applicable to web site design in general, but together he does provide a good arsenal of talking points if you’re ever doing a bid for a consultancy firm.