Use Keyboad And Mouse On Your Xbox 360
If you (like many) found the use of controllers for FPS games on consoles, you will be able to hook up a keyboard and mouse to you Xbox 360 and start fragging. The XCM XFPS 360 makes it possible to connect a USB or PS/2 keyboard and mouse on your Xbox 360, as well as a PS2 DualShock controller, if you prefer those. Only downside is that this is probably not an authorized peripheral by Microsoft, and it will probably be banned for giving an unfair advantage to those with a keyboard and mouse.
Via TeamXbox