One of the most unusual I have seen in a while is the cordless oscillating multitool. A gal I know has one of these, she has glued some foam and layer of leather over one of the attachments and uses it as a super vibrator. Unlike many power tools these don't spin or rotate, the attachments simply vibrate side to side very fast and that vibration is intense, way more than even the most kickass vibrator I've ever seen.
They come in various brands and price ranges, hers is a cheap "home brand" one but for her purpose works a treat!
Just in case you're interested, they look like this;
![tool.jpg tool.jpg](https://www.kinktalk.com/talk/data/attachments/1/1143-da349b4153f41febb38c32eb73646129.jpg)