Annual Report Gallery
Downloadable and printable annual reports from Fortune 500 companies (though some only in Adobe Acrobat format)
Search through 60,000 companies with web presences, public or private, by industry, name, geographical location, and, with free registration, by sales, number of employees.
Search SEC filings of public companies
Fortune Global 500
A marvelous tool from one of the great business information publishers allows you to choose any or all stock exchanges to search by any or all industry groupings for stocks that meet up to 20 investment criteria. The resulting list of companies is clickable. For each company, you can get a profile, then click for SEC filings and historical information (and more info yet if you're a subscriber to Hoover's).
Even without a subscription, there's a fair amount of free reports and other financial data on companies and industries here.
Search latest stock data by company name or ticker symbol.
Standard Industrial Classification Scheme:
since much ranking of businesses is done by SIC, here is how to find out what the SIC number is for a company's product or service
Company index. profiles by industry, stock tickers, etc.