I have seen the technology come and go.  Some of it was good, but it didn't stick.  I have seen 3D cameras come and go (in the 80s) and sort of come back.  Mini CD and DAT recorders and players.  Car phones that had to be installed, and actually looked like an old home phone. But now we have cells so we don't need them.

The Kodak Disc camera - not a bad idea, but tiny film made lousy pictures - most cell phone have a better camera now.

What are some good ideas that didn't stick or find a market?

Digital typewriters.

The gamecube.

Not so much of a device but it was a nice feature:

Picture on picture.

blu-ray players, there are still so many people without one but they all bought a huge plasma or lcd tv years ago

I remember that!

My old monitor can do it.  I did it a few times, but it doesn't have HDMI so I never got a good TV signal on it.

Now it seems multipule monitors have offered a seperate solution.

Anyone remember, in the early 90's food boxes, that do not need to be refrigerated, I think they were called "Top Shelf."  But I can't fun much about them.

1. Dreamcast
2. Neo Geo Pocket Color
3. Windows CE devices (PDA and Tablets)
4. Windows Phone 7
5. Sega Saturn
6. Sega CD
7. HD DVD (Cheaper, Faster, and just as HD as Blu-Ray)
8. Japanese Xbox 360
9. Virtual Reality Headsets
10. Turbo Duo

Pretty much this, except I'm glad windows phone 7 didn't catch on.

Super powered alarm clocks.

steel battalion
http://upload.wikimedia.org/wikipedia/commons/e/e7/Steel_Battalion_controllers.jpg