Xbox 360 wireless network adaptor, allow your xbox 360 to connect wirelessly to your router for wireless gaming! No need for long network cables, or location restriction!
Found in store at tesco for £39. Also available online at this price, however is currently out of stock.
I managed to get mine today for £35.10 from PCWorld by price match and then an extra 10% off! So really, as long as you live within 30miles of a tesco from your closest pcworld or currys, you're laughing!
And to all the people who are going to say "oh there is a new adapter coming out" yes, there is, but its an N type adapter, so unless you have 802.11N enabled routers, then it is a pointlessly more expensive option for no gain in performance if you have only 802.11g equipment! (Which is more than enough for Xbox 360 for online and network streaming and online play anyway!)
Enjoy people :)