AirPort Extreme MAC Address Changer 1.1Free
AirPort Extreme MAC Address Changer changes the Mac address of an AirPort Extreme card by modifying the AppleAirPort2.kext kernel extension. The Mac address change will remain set until the kernel extension is updated by an Apple update or the program is run again.
However, this app modifies and loads/unloads a kernel extension. There is the possibility something could go wrong, which will result in you having to enter specific terminal commands or, in a much rarer case, have to reinstall the AirPort Extreme kext.