Bit of a random one but I give kudos to the winged corkscrew. That's the type that has two levers on each side, which you push down to raise the cork. Wikipedia tells me it was invented by one Domenick Rosati and patented in 1930. Why do I like it? Makes pulling a cork easy, and the design is simple and elegant.
There's a lot wrong with this design. It is perhaps reasonable to use on new wine with pristine corks. But corks are a natural material, so they have a lot of variability, and they do degrade over time. If you open a lot of wine (e.g., if you are a waiter or sommelier) or you drink wine at many ages (e.g. if you are an aficionado or collector) then you need more control in where you place the worm in the cork and how you control the extraction of the cork (for instance giving lateral pressure). This is why you will never see people who routinely open wine as part of their jobs with a wing corkscrew.
(Even worse, wing corkscrews are most likely to have an auger type of worm rather than an open helix. This is not inherent in the design of the corkscrew, of course; many wing corkscrews have open worms. Just something to watch out for if you are buying one.)
