I had a thought about this after my PocketUAE specific question and i think it would be a handy feature for *any* UAE port.
Imagine any launcher, such as WinUAE's and PocketUAE showing a graphic of an amiga keyboard, joystick and mouse and allowing you to click on any of the keys (and joystick and mouse buttons and their directions) and then pressing any key on any attached input device to bind that key.
Keys that are bound would be highlighted and assigning a different key to an already assigned input would remove the binding from the original key.
This way it's totally extensible for any device, especially portable computers and even mobiles and would also allow config files of particular games to be easily created by the user with key,mouse and joystick mappings to suit each. The config file would just store entries for each key binding along with a code such as
JOY_UP 0x12
JOY_DOWN 0x18
JOY_LEFT 0x17
JOY_RIGHT 0x19
JOY_FIRE 0xE3
KEY_F1 0x11
KEY_F2 0x10
in this scenario the original amiga game might use F1 and F2 for load and save game, respectively and i've bound then to particular keycodes generated by my device.