Hi,
Michael has developed a nice mobile wlan hacking device. Unfortunately my UMTS provider is very unstable at the moment, so I have no internet at home. Happily Michael brought his Netgear WGT634u to me and we had a short search, if any open network is available. Yeah, just few seconds later he had a stable and free internet connection.

On the picture you see a battery pack powering the wireless router.
He choosed Netgear WGT634u, because it contains a Atheros based wireless card. Together with the madwifi-ng driver you have a full featured wireless radio, which can be used to search for new networks and being an access point for wireless clients at the same time. The virtual access point (VAP) feature is not only usable to have a private WPA secured network and a public hotspot system on a second AP, like Fon is using it on their Foneros.
Happy hacking
Waldemar, now ordering a battery pack ...