I use the Buffalo router mentioned in carbontiger's link for my WiFi router with DD-WRT firmware. If you have an old WiFi router around or can get one cheap, this is the way to go if you have the patience to get it flashed properly. You can not only configure it as an ethernet bridge, but you can boost the signal as well.
I use a Netgear WGPS606 wireless print server/bridge for my kids 360. I got it for $30 at Microcenter, but YMMV. This works like the one spydey uses. It is a Wireless print server with an ethernet bridge.
I have another WiFi router that I just learned can be configured as a wireless bridge with the original firmware. It is a ZyXEL P-330W. I got it for $5 after rebate, but I think it is about $40. I used this at my inlaws for a stay there since a cable would not have worked.
On these devices, you connect the ethernet port on the 360 to the device with a straight through cable, so if the bridge is configured correctly it is pretty much plug and play. If you don't run DHCP, you will have to put a static IP address on the 360, but that is the same for all devices.
A note on streaming video - wireless works with SDTV, but not HD. It should be fine for Netflix since the bottleneck would be your Internet connection. I run a Media Center PC and I need to run cable if I want to watch an HD stream from it to the 360.