The Pocket Pittie

Built to interface with the XBOX Accessibility Controller, this joystick will register as either a left or right joystick depending on which USB port it's plugged into. 

While it isn't best for PC usage as it shows up as a D-Input joystick (most everything uses X-Input nowadays and the D-Input is required by the XAC), I can make this work as a standard joystick or have it emulate WASD and a USB keyboard so you can use it with any game. 

I've built some variants with a suction cup so you can attach it to a glass table. Some people lay it on its side and use their thumb to operate it while gripping the majority of it.