Here are some of the online resources that let you search for business listings using a ZIP code:
ZIPCode2Business - Searches over 800 business categories by ZIP code. It provides efficient and relevant search engine with comprehensive business listings thus giving you the accurate classification of the business services in the United States.
Google Local - Lets you find businesses by company name, industry, keywords, address and zip codes.
NAICS US Business Directory - This is a pay-as-you-go tool lets you find NAICS codes, SIC codes, DUNS numbers, company size information and more using phone number or company name and zip code or company name and full address.
Tip! Hoovers.com shares Tips on Researching Company and Contact Information.