To obtain company information including directors, results and turnover:

UK: www.hemscott.co.uk/hemscott

US: www.hoovers.com

www.carol.co.uk
gives you Corporate Annual Reports OnLine

Dun and Bradstreet
Have a lot on the net.
To see if there is a free database for your country
For the UK
For the US
For international companies (you get charged for this one!)

and for an outsider's view:
www.fool.com
looks at company growth, trends and activity through the eyes of small investors.

If you are still foxed:
UK and US Business Directories
Business Directories - worldwide
Trade Directories
Company & Financial Information
Country Information
Market, statistical and economic data.

If you are unsure of what company you want, The biggest queues at the library (but not online!) are for Kompassand Kelly's

And if it is marketing information you are after
Marketing Resources on the World Wide Web