MacSpoofer is a FREE mac address spoofer for Mac OS X. 
After installing MacSpoofer you will be able to change your MAC address from the system preferences. It's very easy to use and works for all your network devices.

Supports Mac OS X Snow Leopard (10.6) and newer (including 10.6.4 and Mac OS X Lion).
Windows user? Click here

See the screenshots or Download MacSpoofer right away!

6. March 2013 Version 1.0 is now released!