Joysticks and other devices that plugged into the ADB ports on your older Macintosh or keyboard are not directly compatible with current Apple products with USB ports.
A number of manufacturers have made USB to ADB adapters available. Check the Apple USB page referred to below for more information on adapters.
Here are some related articles on connecting older peripherals to Apple products with USB ports:
For further information on USB in Apple products, visit
http://www.apple.com/usb/