The ring is conceptually kinda neat, but the fact is nobody is going to use one--it's just not practical. And if you take a long view "this is the bleeding edge" perspective, it's all about non-contact motion tracking (XBox, Myo, those laser keyboards, Samsung phones, etc), so it's a dead end anyway.
The posture-checker is silly, but I actually preordered one a while ago for the simple fact that I have terrible posture and I figure if I wear it for a month or two and have it buzz me when I slouch it may work to train myself to not slouch so much. I've tried more traditional means of improving posture and it hasn't worked, so why not give some wacky technology a shot. Basically the same as any other biofeedback device, which have existed for quite a while, and are used by physical therapy outfits to pretty good effect.
The whole angle of having it make you more confident or all that garbage is ridiculous, though, and if I found myself wearing it for more than a short period of time I'd throw it away on principle.
The cube? That's basically an SNL parody. Or a product developed by people who either don't have pets, or shouldn't.