The Aerial and Normal Mouse
Even optical mice don’t work particularly well on a shag pile carpet (I often “work” whilst lying down). So here’s an answer the aerial mouse, works as both a regular mouse but can also be turned upside own and used in the air.
The mouse detects which mode it is being used in and adjusts itself accordingly otherwise your cursor would move in the opposite direction to what you were expecting (now that would take some getting used to).
You can get the USB Wireless Space Mouse EZ (phrew) for Rare Mono for $35.67.