(from mr. townsend of nycwireless fame): "In answer to the long held question, can a TiBook with one Wifi card act as a repeater and relay access to everyone else in the room without them having to pay, the answer it turns out is yes. How do we do this? Well, first turn off the built-in Apache installation on the OSX machine that is online. Edit httpd.conf to load mod_proxy (there are about 20 or so lines to uncomment). Turn Apache back on. Go to network prefs, and find out your assigned IP address. Write it on a piece of paper, and pass it around the room, telling them to set it as their web proxy."