The history of technology is littered with the bodies of brilliantly innovative devices that failed in the marketplace. Maybe they were ahead of their time; maybe they were crushed by unworthy competitors; maybe we were all just too stupid to buy them. What was the very best machine that deserved to succeed and didn't?
I have many picks, but I think the one that hurts most is the NeXT computer. Its OS was full of delightful BSD, plus its form factor was gorgeous (matte black, mmmm), and it was one of the most ridiculously powerful desktop computers for its time. But nobody bought it. Its constituent parts -- well, mostly its software -- were eventually used to build the first web servers. Meanwhile, in some parallel universe, there are people enjoying an entirely different set of machines that evolved from the NeXT rather than the iMac.
What piece of tech would you nominate for greatest commercially unsuccessful device? Post pictures, videos and links to your choice so that we can all enjoy what could have been, and weep for what is.