Lemons & Co.
In addition to coitus interruptus, methods employed in the vagina were frequently used to prevent pregnancy.
Papyri from ancient Egypt describe mixtures and preparations that women applied to their vaginas before having sex.
In the distant past, small sponges were soaked in a variety of spermicidal substances. The vaginal sponge, which is still available, provides evidence that these methods can be effective to a certain degree.
It is said that Casanova discovered the contraceptive effectiveness of lemons in the 18th century: the juice was squeezed from half a lemon, which was then placed over the uterine opening like a cap.
Descriptions of a number of barrier methods in current use can be found at http://www.cervicalbarriers.org/information/images.cfm