that's an adapter that u can get which allows connection of up to 4 wireless 360 controllers. It's pretty cheap, I used to have one until it got stolen when i dormed at college (awesome).

My room mates and i would emulate the n64 mario parties and go ape shit that way XD

http://cgi.ebay.com/wireless-PC-USB-controller-receiver-Adapter-fo-xbox-360-/390231396456?pt=Video_Games_Accessories&hash=item5adb9a9068#ht_1210wt_817

It's worth it :)