The ephemera assemblyman blog has a mesmerising gallery of last century stage hypnotist posters that are an irresistible combination of camp send-up, schlock horror and roll-up roll-up razzmatazz

see the Library of Congress' Performing Arts Posters [link]
the amazing Circus Museum [link]
Magic Posters [link]
Raffaele De Ritis' Novelties and Wonders [link]
for even more links see the Cabinet of Links [link]