I put a USB dongle in a coffee can, it more than doubles the signal strength in my case.
I just followed the instructions for a circular waveguide for the placment of the dongle inside the can.
There is also a web site showing amny different variations of USB WiFi adapters used with reflectors at: »
www.usbwifi.orcon.net.nz/Once the connection is made, one could use ICS (windows) to share the connection with other PCs.