I use a high powered wifi adapter AWUS036H made by Alfa Networks.  It  makes
for a much stronger and longer range connection.   It pulls  power from 2 USB
ports on my older laptop so I have to use a converter or the  battery life is
short.  700 milliamps I believe.   ~$79 on  ebay.
The software allows you to see the comparative strength of the signals
though not as well as netstumbler.
With a high gain antenna I bet you could get miles of range.

Steve

In a message dated 6/4/2008 9:02:40 P.M. Eastern Daylight Time,
starwagen@GMAIL.COM writes:

RE: WiFi  Range Extenders/Antennas
This post will probably prove beyond any doubt my  near total ignorance on
this subject, but here goes.
Of all the links  posted in this thread I've only seen one that might (at a
high cost) be  usable with the newer laptops, all the rest pose problems.
Laptops sold in  the last couple of years have built in WiFi antennas,
connected to the  hardware/software that comes with/in the laptop.  BUT no
external  connection for an antenna.  For my previous laptop I used a  PCM/CIA
card with an external connection for an antenna.  That worked  fine, even
borrowed and hooked up a home made 'Pringle can' antenna to play  around with
(and yes, it worked, could pull in several open nets in the  neighborhood
that didn't show up otherwise).
So what many of us are  looking for is something that will probably plug in
to a USB port and the  software to use that signal instead of the signal
coming from the built in  antenna.
BTW, if I'm missing something in the links I've seen so far, I  apologize.  I
think I only saw one item that used the USB port but the  price was way high.
So if anyone has a link to a product for use with  current model laptops,
that will extend the range for WiFi, I'd appreciate  it.  What searching I've
done has produced no usable solutions that  don't cost an arm and a leg.

**************Get trade secrets for amazing burgers. Watch "Cooking with
Tyler Florence" on AOL Food.
(http://food.aol.com/tyler-florence?video=4?&NCID=aolfod00030000000002)