I have seen some strange peripherals over the years. Many of the strangest are computer mice with tons of buttons or strange designs. Many keyboards and mice are designed to reduce pain for users and to reduce repetitive injuries.
If you like your current mouse, but want more comfort when using the thing some new gel pads called Pad and Click have surfaced. The pads are made from squishy gel that have adhesive on the back.
You stick the large round pad to the mouse where the palm of your hand would sit. The two finger pads sit on each of the mouse buttons. The idea is that the gel is soft and comfortable and allows your fingers and had to be in a more natural grasping position. The thicker arthritis versions sell for $5.99 and the normal versions sell for $4.99 on Amazon.