These resources are from Kate Pittsley's fantastic article "Where to advertise: Media planning resources on the web."
To get you started, advertising and marketing vocabulary is defined at these sites:
American Marketing Association (AMA) Dictionary. The entire AMA Dictionary contains more than 4,000 terms and is regularly updated. Access: http://www.marketingpower.com/_layouts/Dictionary.aspx.
IAB Interactive Advertising Wiki. The Interactive Advertising Bureau (IAB) has a collaborative glossary to keep up with terms for new forms of advertising and new waysto automate ad purchasing. Access: http://www.iab.net/wiki/.