I have created a new library for Joystick Shield, which can be bought from Sparkfun. You can find it at JoystickShield - Night Dreaming (by Sudar)
The source code for the library is available at GitHub - sudar/JoystickShield: JoystickShield library for Arduino
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.