The advent of the Web has created more Financial data than anyone can read.
Finance has stock quotes and financial news links section.
It also has a good Frequently Asked Questions section. CNNfn. is an excellent site with Stock Quotes and interesting business stories. Bloomberg is an excellent site for financial information and has more information on non equities than some of the other sites. Daphyne Thomas maintains the list of links on her web-site. If you are interested in security law, the best site that I have found is from the The Securities Lawyer's Deskbook from the University of Cincinnati.