Please don't kill this thread!
I have read everything relating to joysticks on these forums and I have personally used three usb joysticks with the gp2X.
The first recognised the analogue controller only when it was pushed to the maximum in any direction but not the digital d-pad on the same controller. The second was an arcade style joystic and six button pad that did not waork at all (not in main menu or any emulator).
Number three was an old PC usb joypad that was the same layout as a megadrive II (saturn) controller with six buttons that when using the serial cable with both the breakout board and cradle (I own both) showed that it did not recognize it as a joystick in MAME GP2X or main menu. (not sure if 3.9 or 4.0).
I own two GP2Xs and am trying to work out if I should hold on to the second for my arcade cabinet (currently running an XBOX that recently died) or switch to a P4 (or AMD) for emulator use for my cabinet. I know the advantages to using a PC but I really want it to boot into MAME as my GP2X does but the only controller I can currently use is my GP2X which is crap for arcade play.