Know-How Exchange : Advertising/PR

What specific methods would you recommend for finding leads/customers for my communication consulting company? We consult on communication strategy, train and coach business leaders and managers on communication skills, and offer speechwriting, video production, and other communication help. We are not yet narrowing our focus because we don't know who is most in need of this, but our experience is with large industrial companies (Fortune 500). We think we'd like to work with smaller ($100-500M) companies that have some outside visibility and perhaps are publicly traded (we have extensive experience helping with analysts' presentations). Can anyone help with where we can find lists of these smaller/medium-sized companies and names of contacts therein? Thanks. Susan