Signal Snowboards does something like Google's 20%, where every Third Thursday they just have fun making whatever-the-heck sort of snowboard they want. From the start of every video:

This is Every Third Thursday, a chance for us to have some fun in our factory, get creative with board design and materials, just get spontaneous and come up with a theme - and build it.

A month after Steve Jobs passed away, they did the iBoard.

Every Third Thursday - iBoard

Also worth checking out: (playable) Fender bass-guitar board, their backcountry surfboard. LEGOboard, xylophone-board, the list goes on and on.