Do you have extra keys on your keyboard, mouse or laptop that are never used? For example, you may not be a Korean but buy a keyboard which has Korean- specific keys. Or you may buy a 7-button mouse but only use 3 of them.

xbindkeys can help you fully utilize your resources. Install xbindkeys and xbindkeys_config, which is a GTK program for configuring xbindkeys. Then start xbindkeys_config. When it requires a key input, just press the key or button. Then add an action for it. Quite easy indeed.

Otherwise, you can also directly edit the ~/.xbindkeysrc file, if you know the key code for those unfamiliar keys such as Hangul_Hanja