I'm not aware of any wireless network attached storage (NAS) devices as they would have to run their own wireless software to connect to the wireless network.
Also, for transfer speeds, you are much better off connecting to the router and network via cables as this will give you a steady connection rate.
I use the Buffalo Linkstation which has the added advantage of a USB print server and FTP server built in.
There are some others on the market which you can connect using an ethernet connection - look on Dabs.com or similar for Network Attached Storage.
Be aware also that the Netgear (as well as the Buffalo Linkstation) format the drives in a proprietary system format so you cannot just unplug the hard disk from it and plug it into your computer to read the files.