Having recently procured an Xbox 360, I was wondering if there were any deals around on extra controllers, wired or not (I've got some Audio to surf, so I was already in the market for one of the wired ones beforehand).
Buy.com has wireless Xbox 360 controllers for $40, $10 off retail. Then, you can use GCO to get another $10 off. They also have the wired controllers for $35.