Excellent Marketing Web Pages from Entreprenr.Com
http://www.entrepreneur.com/marketing/index.html
About.Com Marketing Articles
http://marketing.about.com/
Market Research World - Overview of the Marketing Field with Articles and Resources
http://www.marketresearchworld.net/
Marketing Plans, by Industry - BPlans.Com - Some free, some require payment
http://www.bplans.com/sp/marketingplans.cfm
Principles of Marketing Tutorials - Know This.Com
http://www.knowthis.com/principles-of-marketing-tutorials/