Here's a massive thread...
http://pipesmagazine.com/forums/topic/a-few-cool-vintage-ads
It's a huge jumble and a bit of a mess, my later historical posts have more focus,
like these...(my interest is mainly in the old UK tobaccos)
http://pipesmagazine.com/forums/topic/players-airman-survey-of-a-long-gone-tobacco-and-etc-very-image-heavy
http://pipesmagazine.com/forums/topic/willss-capstan-navy-cut-a-short-salty-survey-image-heavy
http://pipesmagazine.com/forums/topic/balkan-sobranie-notes-quotes-links-and-pretty-pictures-image-heavy
http://pipesmagazine.com/forums/topic/a-very-short-history-of-players-digger-tobacco-gtimage-heavy
http://pipesmagazine.com/forums/topic/st-bruno-the-patron-saint-of-pipesmokers-image-heavy
http://pipesmagazine.com/forums/topic/the-big-huge-gigantic-gallahers-gallery-very-image-heavy
...there's more, but that's a good grouping.
A google image search of specific brands usually gets a lot of results too.
One of the best compilations I've come across is this wonderfully titled blog,
Tobaccosophy
http://tobaccosophy.wordpress.com/anuncios-vintage/
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