I recommend the Netgear Ethernet wireless adapter. It is a wifi adapter, but it isn't USB... it plugs into the Ethernet port on your electronic device. I bought this for my older 20gig PS3 which does not have built in wifi (I also have a newer PS3 with built in wifi).
From the Manufacturer
Connect any Ethernet-enabled device to your wireless home network with the NETGEAR WNCE2001 Universal WiFi Internet Adapter. The adapter is perfect for home theater devices such as the Xbox 360, PS3, TiVo, Blu-ray player, and more. And thanks to its elegant, compact design, you'll save space and have a lot of flexibility in choosing where to place it.
Universal WiFi Internet Adapter
At a Glance:
Adds wireless capability to any Ethernet-enabled device
Works with Xbox 360, PlayStation 3, TiVo, Internet-enabled TVs, and more
Wireless-N for fast performance
Push 'N' Connect provides easy security
The easy-to-setup WNCE2001 brings wireless-N capability to any Ethernet-enabled device.
Dynamic LEDs display real-time network connection status. View larger. Wireless Connectivity for Your Ethernet-Enabled Devices
More and more of today's home theater devices are Ethernet enabled, including TiVo, VUDU, Blu-ray players, Xbox 360, PlayStation 3, Internet TVs, and more. With this NETGEAR adapter, you'll be able to cut the cord and use a wireless connection to network your devices.
With the WNCE2001 Universal WiFi Internet Adapter, you will no longer need to buy individual proprietary WiFi dongles for the TV, Xbox, etc. because WNCE2001 works with all of them. You can simply plug it into the device when you need to and share it among multiple gadgets.
Wireless-N Technology for Fast Performance
The WNCE2001 adapter supports Wireless-N (2.4 GHz 802.11n) technology for outstanding speed and performance, keeping pace with your home theater devices. In addition, it is also backwards compatible with 802.11g and 802.11b networks.
The adapter can also repeat 2.4 GHz WiFi signals from devices made by NETGEAR and other brands, and it features dynamic LEDs that display real-time network connection status.
Push 'N' Connect for Easy Security
Setting up a secure connection couldn't be easier with NETGEAR's Push 'N' Connect technology. Push 'N' Connect using WiFi Protected Setup (WPS) offers true plug-and-play simplicity by requiring you to simply push the Push 'N' Connect button on your router. In addition, the adapter also supports WiFi Protected Access (WPA2-PSK, WPA-PSK) and WEP encryption.
Compact, Smart Design Can Use USB for Power
The Universal WiFi Internet Adapter is a compact device that measures just 3.2 x 2.4 x 0.7 inches, giving you flexibility in choosing where to place it. In addition, the adapter can be powered by either the included power adapter or with the USB port. By using the USB port, you can avoid using an additional power outlet, and reduce exposed wires in your home.
The NETGEAR WNCE2001 Universal WiFi Internet Adapter works with Windows 7/Vista/XP/2000, Mac OS, UNIX, or Linux. It is backed by a one-year warranty.
What's in the Box
Universal WiFi Internet Adapter (WNCE2001), power adapter, and mounting kit.