Dumping the Wireless Passwords in Windows
I quote:
WirelessKeyDump is a console application (Command Prompt) that dumps the list of all wireless keys stored by the wireless networks module of Windows operating system.
This utility works on any version of Windows starting from Windows 2000 and up to Windows 7/2008. On Windows 7/Vista/2008, you must use it from a command-prompt window that was started with ‘Run As Administrator’. On x64 systems, you must download and use the x64 version of this tool.