A huge database of ads, old and new, organized by decade, type, and most popular.
A site dedicated to explaining and criticizing ads. Some reviews are critical, while some are complementary.
Contains a journal, a museum, a library, and more - all related to advertising.
Contains full length ads that can be rated and reviewed on the website. Other reviews can be read and responded to.

Subliminal Influence
Explains different kinds of priming in the context of asking "does subliminal influence work?"
Developments in Research on Subliminal Advertising
An article by Moore and Pratkanis on recent developments in research on subliminal advertising
History and Discussion of Subliminal Advertising
An article on subliminal advertising, including a history of work on the concept and a discussion of the FCC's view on the topic. Contains some excellent links.
A site that takes you step by step through the different and increasingly well hidden levels of subliminal messages in advertising.
Ad Access
Images and database information for over 7,000 advertisements printed in US and Canadian newspapers and magazines between 1911 and 1955.
Ad Munch
Provides articles and resources for effective advertising, as well as several archives of ad campaigns.
Coca-Cola Advertisements
Fifty Years of Coca-Cola Television Advertisements: Highlights from the Motion Picture Archives at the Library of Congress. Presents a variety of television advertisements, never-broadcast outtakes, and experimental footage reflecting the historical development of television advertising for a major commercial product.
Ad Errors
A fun page containing ads that have spelling errors. "The quickest way to turn off a good segment of potential buyers is to make a stupid typographical or grammatical error in your ad..."
Luerzer's Archive
Contains many ads, most without words on them. To get access, you must run a search in the bottom left hand corner of the main page.
Posters from the WPA
The examples on this page demonstrate the breadth and depth of the WPA collection and the styles and content used by the WPA to advertise varied programs and campaigns.
Powers of Persuasion
Poster art from World War II. An online exhibit from the national archives that presents the advertisements of W.W.II.
Emergence of Advertising in America
Presents over 9,000 images relating to the early history of advertising in the United States. The materials, drawn from the Rare Book, Manuscript, and Special Collections Library at Duke University, include cookbooks, photographs of billboards, print advertisements, trade cards, calendars, almanacs, and leaflets for a multitude of products. Together, they illuminate the early evolution of this most ubiquitous feature of modern American business and culture.

Subliminal Perception
Another good article on cognitive psychology's approach to subliminal perception.

Brought into the Fold
Scientology as a case study on influence and persuasion in religion, which applies social psychological theories to Scientology's practices. Discusses the Elaboration Likelihood Model, and Cialdini's principles of influence.
Is Subliminal Influence a Threat?
Excerpt: "Potentially, yes, subliminal influence of various kinds could represent some sort of social threat. It isn't likely that people could be turned into automatons by subliminal influence, but it is arguable that we are already greatly, even unfairly, being influenced by carefully crafted psychologically sophisticated persuasion tactics."
Is Subliminal Influence Used in Advertising?
Excerpt: "If we use the term subliminal in the way that it is commonly used, to mean any sort of hidden message, then yes, advertisers do frequently hide their message. This might even be considered a standard advertising practice. Advertising agencies are paid to effectively craft the message "buy this." And we know that historically, they haven't found it effective to simply inform us of the benefits of the product. They rely strongly on emotional appeal and reinforcement principles of various kinds."
What is Subliminal Influence?
Excerpt: "The term subliminal is technically archaic, though it is still in common use. The problem is that it is hopelessly bound to the concept of a well-defined sensory threshold, a concept made obsolete by the introduction of signal detection theory into psychology."

Why are some experts skeptical about subliminal influence?
Excerpt: "There was once a legitimate scientific controversy over whether subliminal perception really occurs or not. The question was whether someone can perceive something unconsciously. All kinds of experiments were performed to try to prove that we were perceiving something without awareness of it."