The Eisner Museum (part of the Milwaukee Institute of Art & Design) is the leading museum for the history of American advertising and regularly mounts new virtual exhibitions:
www.eisnermuseum.org

The John W. Hartman Center for Sales, Advertising & Marketing History at Duke University, Durham (North Carolina) is a gold mine of early American advertising (1850-1920):
repository.duke.edu/dc/eaa

The site of Frans Wilbrink, a collector and authority on the subject, offers an excellent overview of Philips advertising:
philipsreclamekunst.nl

Entry to the virtual exhibitions of the French Musée de la Publicité, Rue de Rivoli, Paris:
www.museedelapub.org

The site for the history of British advertising is the Historical Advertising Trust, Norwich, UK, which was formed in 1976:
www.hatads.org.uk

Heidelberg, Germany, has a unique packagings museum with many classic items illustrating the history of packagings:
www.verpackungsmuseum.de

The Austrian Lürzer group has an extensive, international collection of digital advertising material:
www.luerzersarchive.net