7 tech revolutions that flopped

TV makers keep promising that 3-D technology is really ready for prime time. If your only experience watching television were at the annual Consumer Electronics Show in Las Vegas, you'd be forgiven for thinking everyone in the world owned a 3-D TV -- they're everywhere at tech's biggest expo.

The truth is no one wants to wear dorky-looking glasses while watching TV, and there are hardly any TV stations that broadcast in 3-D.

ESPN made waves when it launched its own 3-D sports network in 2011, thinking it could usher in the era of 3-D TV the way that it almost single-handedly brought high-defnition into living rooms across the country. But it never took off, and ESPN shuttered its 3-D network just two years later.