The annual "Leading National Advertisers" issue from Advertising Age is now online, with added content from AdAge's Data Center. For the top 100 "LNA", media spending is listed. For large brands within a company (e.g., Chevrolet, Buick - within GM ; M&M's - within Mars), media spending is also listed.
AdAge's Marketing Fact Packs are available to download within the DataCenter. Non-subcribers can fill out a form to download, at Adage.com/Resources ; "for personal, non-commercial use only".
Also consider browsing through our online historical newspapers - for the Atlanta Constitution [1881 to 1984] and New York Times [1851 to 2011]
The Library has acquired backfiles (as-is, newsstand versions) of some newspapers, general periodicals and business periodicals - ad content is searchable and viewable.
Newspapers: New York Times (1851-4 years ago) ; Atlanta Constitution (1858-1984). For more, see "News and Periodical Articles" page/tab.
Business periodicals: Fortune (1930-2000)
Women's Magazine Archive - includes: Better Homes and Gardens(1922-2005) ; Cosmopolitan (1886-2005) ; Essence (1970-2005) ; Good Housekeeping (1885-2005) ; Ladies' Home Journal (1885-2005) ; Parents (1926-2005 - some gaps) ; Redbook (1903-2005 - some gaps) Seventeen (1944-2005) ; Town & Country (1846-2005 - some gaps) ; Woman's Day (1937-2005)