[kijin]

I haven't personally tried sticking an antenna through a wok (just putting one behind the router was enough for my purpose), but rumors say that you can achieve a range of several miles if you do it right.

[walshemj]

There are online calculators http://www.radiolabs.com/stations/wifi_calc.html note that the cable loss mentioned is the antenna feeder cable

And Cisco Press do some good books on the basics of WiFi network design.