Financial Ratios 

Market Watch
This site provides one of the best sources for comparing ratios and other company financial data. Select a public company in the industry you are researching, then click on Ratio Comparisons at the left side of the screen. You will not only obtain financial ratios for the company you are researching, but you will also find ratios for (1) the company's industry, (2) the economic sector in which the company operates, and (3) the S&P 500. This is a FREE resource.
Money Central
This is a good source for ratio comparisons. This is a FREE resource.
Big Charts Market Watch
"The world's collest investment charting and research site." This is a FREE resource.
Hoovers Online
Hoover's Online puts unbiased business informationa nd analysis at your fingertips. Hoover's editorial staff of some 80 editors and researchers bring vital business information and knowledge to their coverage, updating the site daily to bring our visitors and subscribers the most up-to-date business information in the industry.
Bloomberg Business
Bloomberg L.P. provides data, analysis, electronic filing and financial news to the world. This is a FREE resource.
Yahoo! Finance
This is a FREE source where users can gather a plethora of financial information on companies they are interested in.
The link requires thatyou register in order to gain access to much of hte information, but there is NO CHARGE for registration.
This is a FREE link, and it contains historical ratio analysis for each company. This is very valuable when researching trends.