If you'd like to ensure your small business can obtain some attention and contract opportunities with government and large businesses, you should register for a D-U-N-S number with Dun & Bradstreet. According to the site:
The D-U-N-S Number is an industry standard for keeping track of the world's businesses and is recommended and/or required by more than 50 global, industry and trade associations, including the United Nations, the U.S. Federal Government, the Australian Government and the European Commission.
Your D-U-N-S number is not just a requirement for some opportunities, it's also an identifier for your business much like a social security number (in the US) is for your credit reporting. It will allow large businesses, lending agencies, and the federal government to do credit checks against your business to verify whether or not they wish to do business with you. It would be a shame to do all the marketing necessary to promote your business – only to lose a deal because your business isn't registered and found in the DNB database!
Dun and Bradstreet maintains a database of over 140 million businesses world wide with over 200 million financial records recorded annually. It's just as important to keep track of your business' credit rating and reputation via Dun and Bradstreet as it is to track your personal credit rating.
You can find additional business resources (US) and information on starting your business at the United States Government's Small Business site.