Is there a website where I can find out the annual revenue of a company?

NOTE it must be a public company I believe. If it is private it operates under different rules and info can be impossible to get.

A public company has sold a portion of the business to the public via an initial public offering. IPOs can generate intense news coverage, such as Google’s (nasdaq: GOOG – news – people ) recent deal, and going public can be seen as coming of age for companies in hot sectors.

A private company is held by a handful of people, often the founder and a few others.
Many believe privately held companies are small and of little interest. There are tons of small companies but some big names are also privately held, including Cargill, Ikea International, Mars and Hallmark Cards.

EXCELLENT EXPLANATION Public versus private companies
A public company usually refers to a company that is permitted to offer its securities (stock, bonds, etc.) for sale to the general public, typically through a stock exchange
http://www.answers.com/topic/public-company?cat=biz-fin

For example if it was NIKE

The reuters site is excellent for research
http://stocks.us.reuters.com/stocks/overview.asp?symbol=NKE

Nike, Inc. – Company Profile, Information, Business Description, History, Background Information on Nike, Inc.
http://www.referenceforbusiness.com/history2/99/Nike-Inc.html

Motley Fool great site
http://caps.fool.com/Ticker/NKE.aspx

Business Week Nike Inc.
http://investing.businessweek.com/research/stocks/ownership/ownership.asp?symbol=NKE

SWOT Analysis Nike, Inc.
http://www.marketingteacher.com/SWOT/nike_swot.htm

The Wall Street Journal
http://online.wsj.com/quotes/main.html?type=djn&symbol=nke

Financial Times Great Graph
http://markets.ft.com/tearsheets/performance.asp?s=us:NKE