I've never modded anything before but the joystick on the gp2x is just tooo crap to work with. If it was rubber insted of plastic then at least you could get a better grip on it. Using it to play games like micro machines and zero wing is just unnessarily difficult so I decided to nick the anologe stick from my xbox controller.  
 
First I thought it may be too big but as along as you let it have enough room to breath (stick out) then it works great.
Heres a pic:
		
		
	
	
		
	
And Heres a Crappy Guide (You Will Need a hacksaw):
		
	
As far as I'm aware this hasn't been done before but if it has sorry for posting it twice
h34r:
				
			First I thought it may be too big but as along as you let it have enough room to breath (stick out) then it works great.
Heres a pic:
	And Heres a Crappy Guide (You Will Need a hacksaw):
	As far as I'm aware this hasn't been done before but if it has sorry for posting it twice
	