Macpaint 3D (lost paint program; 1990s)
The original Apple tablet running "MacPaint 3D" nearly 20 years before the invention of the iPad.
The Apple Computer Company needs no introduction. They were a pioneering business in the 1970's and 1980's, and are still a big competitor today. They were responsible for bringing computing to the masses with the Apple II, Lisa, and Macintosh, which was originally introduced via a now-famous Super Bowl commercial in 1984. In 1985, after numerous conflict with Apple's Board of Directors, Steve Jobs was fired from the company he helped found. He then found another company, called NeXT Computer. During this period in time, Apple was starting to lose direction, which led to poor sales and constant threats of bankruptcy.
During this era (which lasted for 13 years), the company produced many prototypes that never made it to market, ranging from mobile phones to home appliances. One of the prototypes that showed potential to be successful was an ultra-thin, drawing board designed for professionals. The board utilized a drawing program known as the MacPaint 3D. The program was a variant of the standard MacPaint application but used a 3D CAD and restrictive touchscreen technology to make it work.
Although the project showed potential, in 1997 Jobs returned to Apple and bought NeXT for a reported $400 million, and soon this project was cancelled along with many others in an effort by Jobs to make Apple profitable again.