I'm not using a joystick, but I have been really focused on incorporating more interactive and performance-oriented modules. For the price, I really enjoy the Sound Machines LS1 light strip for modulation and the Low-Gain Short Bus for live trigger/gate/rhythm manipulation. The FSS Makrow is killer for changing multiple parameters with the turn of a single knob. DivKid Mutes are great. I'll soon be adding a second Mutes module, in fact, so I probably should have just picked up the FSS Stumm in the first place, but I really enjoy DivKid's module. The NE Quant Gemi is a fairly interactive octave switching module. And finally, the Acid Rain Navigator is on my short list.
Which joystick are you looking at?