Here's an example of one.
One guy says it didn't work with his Sidewinder Force Feedback Pro, another guy with different joysticks says it works perfectly. *shrug*
Guess it might not be compatible with force feedback joysticks.
(Compatible with Thrustmaster FCS, CH Flightstick Pro, 2-4 Axes/4-Function and 2 Axes/8-Function controller.) - Which explains why it doesn't work with the Sidewinder FF Pro (4 axes, 9 or 10 buttons, one of which was called a shift button which was used to change the function of other buttons, and a POV).http://www.buzzillions.com/reviews/radio-shack-usb-game-port-adapter-pc-reviews
Radio shack apparently has one.http://sewelldirect.com/USB-to-Gameport-Adapter-for-Joysticks-Controllers-and-Gamepads.asp
And some other one.