Dun & Bradstreet Million Dollar Directory
Over 160,000 public and private U.S. companies are included in this database. Company listings include company names and addresses, lines of business, officers and directors, sales, number of employees, and year founded.

Gale Directory Library from Gale 
The Gale Directory Library hosts the follwing directories;
Encyclopedia of Associations: National Organizations of the U.S.
Encyclopedia of Associations: Regional, State and Local Organizations
Gale Directory of Publications and Broadcast Media
Scholarships, Fellowships & Loans
Ward's Business Directory of U.S. Private and Public Companies
Use it to search, sort and export information from both current directory editions as well as prior editions that are maintained as searchable backfiles. Multiple directories can be cross-searched or users can mine individual directories for the particular kinds of data they contain, such as financial information for companies, circulation figures for publications, and much more.

LexisNexis Library Express
News, Business, Legal and Biographical information including national and international companies, case law, statutes, regulations, legal news and law reviews.

ReferenceUSA
Allows company searches by size, location, and industry. Includes residential information.