TheStreet.com's own web site: http://www.TheStreet.com/ (stock symbol: TSCM), and CBS MarketWatch's website is http://www.MarketWatch.com (stock symbol: MKTW).
 

SEC EDGAR database: http://www.sec.gov/edaux/formlynx.htm.

Type a ticker or company name and then click on submit choices. You can get the company's disclosures here. The 10-Kxxx and 10-Q reports should prove particularly useful.
 

Yahoo Finance: http://finance.yahoo.com/.

You can download past daily, weekly, monthly and yearly price data, earnings data, and a brief analysis of a company. There are also links to news articles about the firm.
 

Business Browser: http://www.library.yale.edu/socsci/databases/bbinfo.htm.

Contains a brief analysis of the firm and its industry.