The single-purpose gadget is very much alive and well. Case in point, this USB tentacle. It squirms. That's all it does.
The USB tentacle is not a hub. It won't open a beer bottle. It won't fire foam rockets at your cubicle mates. It won't charge your smartphone. It just squirms. To improve the visual impact, you might want to invest in multiple tentacles to adorn each port on your computer.
Why would you want to drop $24.99 on a tentacle? That's kind of a high price tag for something that just wriggles around a little bit. Perhaps you're a marine biologist looking to spruce up your laptop look. There's a certain portion of the population for whom this will be a must-buy accessory. You know who you are.
ThinkGeek suggests using the tentacle as a way to show your devotion to Cthulhu. You can try it, but just be aware that Cthulhu won't be dissuaded from feasting upon your soul just because you attempted to pay homage with a cheap gadget. You might as well just embrace the madness and be done with it.