Company web sites can provide a wealth of information, particularly for public companies. Look for press releases, investor information and financials, including presentations and events and filings such as SEC filings, annual reports or corporate social responsibility or "community" reports. Use information from the company carefully and watch for bias or an overly-optimistic interpretation of factual data.
Nexis Uni provides annual reports, 10K financials, and other SEC filings. Open the Business topic section, then open the pull-down under Company Search, on the right side of the display, and select SEC Filings. Enter the company name in the search box and click Find. At the results display open the Sort by pull-down and select Date (newest-oldest).
CogMap: The Org Chart Wiki A Wiki that provides organization charts for companies and other organizations.
The Official Board offers charts for "the world's 20,000 largest corporations."