I have created a new library for Joystick Shield, which can be bought from Sparkfun. You can find it at http://sudarmuthu.com/arduino/joystickshield
The source code for the library is available at https://github.com/sudar/JoystickShield
The main feature of the library (IMO) is that it supports callbacks, which I implemented using function pointers.
I would be really grateful if you can try it out and give me any feedback/comments. Thanks.