Sony Walkman II, circa 1982

Introduced in Japan in 1979 and in the US the following year, the Walkman allowed users to enjoy music while walking, exercising, or using public transport. It changed the way people enjoy music--providing a private experience in the midst of everyday life--encouraging a trend that escalated with the development of the iPod and other digital music players.

This is one of the first 50 Apple 1 computers. Apple 1s were the first pre-assembled personal computers; Steve Wozniak assembled this one in Steve Jobs's family home. Before the release of the Apple 1, owning a personal computer meant building it yourself. Wozniak's refined engineering skills, coupled with Jobs's bold marketing abilities, led to a revolutionary and affordable product--as well as a successful company.

Thomas Edison's electric pen, an ancestor of both the mimeograph and the tattoo needle, was a successful product in the mid-1870s. Users would write normally with the pen, which, instead of a nib, had a needle powered by an electric motor. The needle poked holes into a stencil, which was then used to copy the document. Many businesses found document duplication an attractive possibility.