Each year, a group of librarians publishes a list of the best free websites.  There are several interesting collections of images and advertisements. 

Ad*Access is a collection of print ads from 1911 to 1955.  It covers five topic areas: Beauty and Hygiene, Radio, Television, Transportation, and World War II propaganda. 

The Living Room Candidate: Presidential Campaign Commercials provides access to commericals from 1952 to 2008.   Users can search or browse by topics such as backfire, children, fear, change, or welfare. 

Newseum: Today's Front Pages is a collection of the first page of over 800 newspapers from around the world.